iscsi multipath different subnets Multipathing Configuration for Software iSCSI Using Port Binding Multipathing for Software iSCSI Multipathing between a server and storage array provides the ability to load-balance between paths when all paths are present and to handle failures of a path at any point between the server and the storage. 11. After the server reboots, open MPIO again. I've tried using different subnets, but the MPIO on W2k3 wants them to be in the same subnet. Enable multiple sessions support on your iSCSI Targets, you may refer to here for more information. 1. 1. For dm-multipath you should: then set values like queue if no path, so that IO errors are retried and: queued if all paths are failed in the multipath layer. Note: In iSER configurations, the VMkernel adapters used for iSER connectivity cannot be used for converged traffic. Step 1: IP subnet configuration for AIX host and SVC storage box. 0. Therefore, port 0 of each controller must be in the same subnet, and port 1 of each controller should be in a second subnet. 0: Normally you use different subnets so you can confirm traffic flow. Multiple paths for an iSCSI target with a single network portal . e. An example of MPIO configuration with a performance test showing 200MB/sec using dual Gb NIC’s is demonstrated step-by-step at: How to configure DSS V6 MPIO with Windows 2008 Server. For simplicity the iSCSI Target in this document will be called server, and iSCSI Initiator – client. You can refer to this tutorial to do it. 10) eth2 (192. Step 1: Configure vSwitch and Enable Jumbo Frames The Linux iSCSI driver, which is part of the Linux operating system and which you configure so that the host iSCSI initiators can access the iSCSI storage, does not distinguish between NICs on the same subnet. Install the Windows Server Multipath I/O feature to support MPIO with SC Series storage 1. vSphere Storage VMware, Inc. 10. MPIO is only available on the Synology NAS with two or more network ports. Thanks! If you are implementing an active-active controller storage array, then you should use different subnets for each set of ports. That way, you have additional resilience in case one of your subnets goes down (i. For example, all NIC 3s must be configured to use the same subnet. Assign IP addresses to each iSCSI port to match the subnets for each redundant path. If all Front End iSCSI ports on the Dell Compellent System are on the same subnet, then NIC bonding is the better option since XenServer iSCSI MPIO requires at least two separate subnets. The iscsi-portal commences with querying related target network portals using the initiator name learned in previous step. Microsoft MPIO Multipathing Support for iSCSI-- MPIO is a way that you can increase the overall throughput and reliability of your iSCSI storage environment. 3 . In this document, 172. For more information about failover mechanism in IPMP, see IPMP Support in Oracle Solaris in Administering TCP/IP Networks, IPMP, and IP Tunnels in Oracle Solaris 11. 1. - Routing is required to reach the iSCSI array. To clear the warning, you'd actually have the SAN available on two different subnets and each MPIO enabled iSCSI NIC in the host would be on each subnet. As you get into iSCSI you will find that different solutions recommend different IP Subnet configuration, eg: Equalogic requires one subnet but the MD3xxx series requires separate subnets per NIC port. These 9000-byte frames relieve congestion on slower Ethernet networks that are not using 10 GbE, which gives a performance boost of about 10-20 percent. You have redundancy and maximum performance. You can add more than one san on each iscsi network. 1 iSCSI ping/Nop-Out Figure 5. Those subnets are over-zealous, but for the sake of support-ability, I chose a commonly known subnet mask. 168. 1994-05. MPxIO matches the unique SCSI per LU identifier, and if they are identical, presents one path to the iSCSI driver. If you want to add another path, the volume needs to be unmounted and remounted. 168. 10. Usage of MPIO is recommended for experienced network administrators only. Leave the radio button next to iSCSI Static Target Interface selected and click the green Plus Sign to the right. iSCSI Initiator Properties screen shown in VMware vSphere 5. There will still be a primary discovery address in any case. Virtual hosts are running esxi an we have a redundant storage network and using MPIO from the hosts to our current storage. I've tried using different IPs in the same subnet, but again the MPIO on W2k3 tries to make both NICs hit the same iSCSI target IP. 3 for iSCSI communication. The program iscsi-init can be helpful if you intend to boot your linux system from or install on iSCSI LUN using Open-iSCSI software initiator. The IP addresses for multiple paths need to be specified during volume mount. This will launch the MPIO Properties configuration dialog. The preferred method to do this for SW iSCSI is with iSCSI Binding implemented, but it can be achieved with adding multiple targets on different subnets mapped to the iSCSI initiator. OPTIONS OF CATEGORY L: Subnet=<subnet address> Subnet settings apply to sessions to a network portal in one of the specified subnets, or whose address matches one of the specified addresses. 168. k. SMB Multichannel was designed to solve two problems, first make the path from the Hyper-V host (SMB Client) to the File Server or Scale-Out File Server (SMB Server) redundant and get more performance by using multiple network paths. 168. * and 192. n VMkernel adapters used for iSCSI connectivity exist in different broadcast domains, IP subnets, or use different virtual switches. x subnet is used for iSCSI/StarWind heartbeat traffic, while 172. 1. If you do multipathing correctly, you can pull either switch side/path down and things still work. Configure MPIO or DM Multipathing for the volumes on the host. 201) --| > > Amador, could you point me to a The DM-Multipath package is installed on the client. 8. You you declare it multiple times, but the last one is the only one that will get used. Or a real hardware iscsi/fc card if you needed iscsi/fc diskless boot. NOTE: Not all iSCSI arrays behave like this. e. Featuring Multipath I/O (MPIO), industry leading durability, and our global footprint, the Endurance and Performance iSCSI block storage products are a great fit for a variety of workloads worldwide. =09 In order to do MPIO you need 2 interfaces on the target in 2 different = subnets and 2 interfaces on the initiator in different subnets. This will require a REBOOT of the Hyper-V Host server. Both subnets reside on completely separate physical switching infrastructure, and cannot talk to one another (no route exists between the two subnets). 168. Microsoft MPIO driver or Device-Mapper Multipath (DM-MP) tool integrated in RedHat Enterprise Linux 4 update 2 or later. Use IP network multipathing (IPMP) for load spreading and better failover mechanism. The following illustration shows multipathing setups possible with different types of iSCSI initiators. Chapter 13 Configuring iSCSI Multipath Configuring a Port Profile for iSCSI Multipath DETAILED STEPS Command Purpose Step 1 config t Example: n1000v# config t n1000v(config)# Places you in the CLI Global Configuration mode. iSCSI Subnets and Routing Recommendations VMware vSphere 4. 10 for port 0 on controller 0 and 192. But what about Hyper-V? How I can provide fail over for guests? Any idea? Best Regards . 1. Using istgt(1) we have support for MPIO but the FreeBSD network stack has no support for multipathing in the kernel other than using Use MPIO if you need to support different load‐balancing policies on a per‐LUN basis. Software iSCSI Port Binding is also contraindicated when LACP or other link aggregation is used on the ESXi host uplinks to the pSwitch. This blog post will provide you with some examples. What your EqualLogic is doing (and many other iSCSI arrays, like the P4000/LeftHand I deal with) is iSCSI Login Redirect, where the target (usually from a floating virtual IP) redirects to one of its other addresses on connect. VMkernel adapters used for iSCSI connectivity exist in different broadcast domains, IP subnets, or use different virtual switches. Basic configuration I’m going to create a vnet with two subnets; I want the Gluster replication to happen over one subnet/network interface and the communication between the clients and the iSCSI targets (the Spread iSCSI sessions across multiple physical links or subnets for higher availability of iSCSI devices. Two network cards were physically connected and logically configured to the network IOS as a bonded connection for passing VLAN traffic to subnets A, B, and C. Ex: 2 controllers, 2 iSCSI ports on each controller means C0nic0 and C1nic0 are on the same subnet and C0nic1 and C1nic1 are on the same subnet. If you have dual iSCSI to FC bridges in an FC SAN, iSCSI presents target paths to MPxIO. The UI is a major change from 4. OPTIONS OF CATEGORY L: Subnet=<subnet address> Subnet settings apply to sessions to a network portal in one of the specified subnets, or whose address matches one of the specified addresses. 25. Under the Discover Multi-Paths tab, check the Add support for iSCSI devices check box. For example, if portals and NICs are set up on different subnets, then it is not necessary to manually configure iSCSI interfaces for binding. Y) - NIC2 - (Subnet 172. 0, and 5. 168. Since you have iSCSI SAN, I suggest you go with MPIO splitting iSCSI networks and utilize different subnets. Ensure that STP is disabled, at least on iSCSI interfaces. iSCSI 1. apt-get install open-iscsi multipath-tools mc 4) Set up both NICs eth1 and eth2 on Ubuntu ifconfig eth1 172. on the console of the XenServer and it will report back what the multipath kernel module is seeing. *). Typically, multiple connections and things like MPIO are mutually exclusive -- you have to pick one or the other. The initiator with the IP address 10. The multipathing software handles all input and output requests and passes them through on the best possible path. Write down the IQNs for each ISCSI initiator/HBA to complete the Host Setup Wizard. 20. If I configure a server to connect to the SAN using windows 2008, I need to have the left and right controllers on different subnets (192. So my iSCSI-PG1 will use uplink 1. It is strongly preferred that you mimic this design in terms of using separate IP subnets; using multiple IPs from the same subnet can lead to default routes that negate much of the point of MPIO. Teaming and MPIO for connecting to iSCSI storage has been a confusing issue for a very long time. Multipath interference is a phenomenon in the physics of waves whereby a wave from a source travels to a detector via two or more paths and the two (or more) components of the wave interfere constructively or destructively. 60. will show you what the iSCSI initiator is seeing. iBFT is available: - configures network interfaces using parameters in iBFT; - creates static routing entries to the target IP's if in different subnets; - calls "iscsistart" to establish iSCSI sessions with the target. Let say, we want to configure 4 iSCSI MPIO paths between AIX host and SVC storage box. 6 you have to do the same for the targets, so that you have 1 target per subnet/vlan. Keeping latency low as possible is also crucial. 20. Catches to look for: In your Freenas iSCSI target configuration, make sure you have Allow Hosts entries appropriate for each subnet. 10. 168. 200) --| |-- iSCSI Target (192. g. 7. Then you have to manually add SATP rules because default one incorrectly map to VMW_SATP_DEFAULT_AA or VMW_SATP_LOCAL for SAS version. Sorry the title is a bit of a mouthful. Sorry the title is a bit of a mouthful. I tried (native) multipathing on SLES11 on different VLANs. Multipathing must be configured on each host in the pool. These two addresses should be on different subnets to ensure high availability. 168. Each server has two 10Gbit NIC's, connected to separate 10Gig switches. You should not use network adapter teaming with Microsoft iSCSI Software Target 3. 11 for port 0 on controller 1. Setting up Software iSCSI Multipathing with Distributed vSwitches with the vSphere Web Client. You can put them on the same or different subnets on a Celerra and there is not the issue noted in this article. 2. Add two more sessions like above, Nic2 -> A1, Nic2 -> B2. On the iSCSI Initiator, its best to reserve network cards for storage duties only, and they can not In this example, each iSCSI target is assigned static IP addresses from two datacenter subnets. To ensure iSCSI IP failover operations, nodes in the same I/O group must be connected to the same set of subnets on the same node ports. netlog. 0. Hardware iSCSI HBAs tend to support MPIO over MCS as well as include other features such as Boot‐from‐iSCSI. This is what we've done for years. Configuring iSCSI This is where things got heady and confusing. 168. How to configure a vSphere Distributed Switch for iSCSI multipath MPIO with each path being on different subnets (a. eth1 – 10. I make the server connect to two iSCSI targets. for example : vmk1: 192. 168. If more advanced MPIO features are needed, third-party MPIO software may be used if supported. 04 and a EqualLogic SAN Recently we purchased a EqualLogic PS6000XVS for a KVM environment. 3. 16. co. 10/24 up ifconfig eth2 172. Using dedicated iSCSI host bus adapters (HBAs) is an option, but the less-expensive option of booting directly from an iSCSI SAN using standard NICs can deliver comparable performance. The default iSCSI configuration creates only one path from the software iSCSI adapter (vmhba) to each iSCSI target. If I connect the iSCSI to my Win 7 im seeing 110mb on both. LACP does same failover as MPIO, however comes with performance penalty due to unsupported Multiple Connections per Session (MCS) meaning, it would not performance boost for same configuration. 3 So, if : ESX1 Configuration NIC1 - ISCSI_1 (Subnet 172. Heart Beat network is also not support in NIC teaming. 168. 2. 2 Windows Server support for other MPIO software This guide covers the built-in Microsoft DSM which is fully supported with SC Series arrays. So MPIO will provide iSCSI network redundancy. Multipathing The IP addresses of the interfaces exposed by the server for Multipathing can be in the same subnet or in a different subnet. ) For most circumstances, the throughput afforded with 2-way MPIO is sufficient; but if the project demands 4-way MPIO, and the prerequisite host NICs and switch ports are available, then we must configure the 4-way MPIO. Close everything and start computer management. Using the same subnet with multiple IP's will not provide a proper multipathing config. However, some deployments of dedicated iSCSI networks or subnets to maximize the bandwidth available for storage. Select the software iSCSI adapter on the list and click “Properties” to ensure the adapter is enabled. If you plan to use multiple network adapters for iSCSI communication, you should separate them into their own subnets, set up virtual IP addresses, and then implement MPIO. In an ideal scenario, these network adapters will have different routable subnets, but in this validation, they will have network adapters on the same subnet. Hardware iSCSI HBAs tend to support MPIO over MCS as well as include other features such as Boot‐from‐iSCSI. Depending on the DSM used (or none at all), you create a vmkernel for each network adapter (real or virtual) for each subnet you will be connecting across. 25. E. Executive Summary: SANs provide benefits such as RAID, snapshots, replication, and Microsoft Multipath I/O (MPIO) support. This makes a 1 in MPIO, the 2 iSCSI subnets need to be different, you may map them to same interface, but they should have non-overlapping ips else it can cause path routing issues The networking setup can be different depending on the number of physical adapters we want to use for the iSCSI traffic. It already works if you manually configure multipathing before launching hosted-engine --deploy Example with 2 NIC on the host, 2 NIC the iSCSI host and a single portal on both the interface: On the host: # iscsiadm -m iface -I eth0 --op=new # iscsiadm -m iface -I eth1 --op=new # iscsiadm -m discovery -t st -p 192. The P2000 has 2 controllers, each with 2 10Gbit NIC's. Enable Multipath for the host using the host properties in XenCenter. 1. 90 connects with the iscsi-portal’s IP address 10. Figure 18-2. Multipath iSCSI with Ubuntu 10. In addition, you must be sure to override the NIC teaming active-standby policy so that each VMkernel port is active on only a single vmnic. 25. In this sample scenario, there are multiple VMkernel ports in on different IP subnets and broadcast domains and the target ports also reside in a different IP subnet and broadcast domain. Common example for the use of multipathing is a iSCSI SAN connected storage device. 10. Click OK and Afterwards, click the Add button. 10. See full list on c-amie. The performances are affected so by this behavior. 1:3260 -A vmhba33 Configuring Multipathing for Software iSCSI. The port binding is set up under the Network Configuration options in the software iSCSI adapter’s properties: Let’s dive right in to some real world implementations of port channels for both iSCSI and NFS, and I’ll do my best to explain why I think it’s best to avoid port channels. As for the warning, it is just a warning. Select "Microsoft iSCSI Initiator" as local adapter, Nic1 IP as initiator IP, B1 ip as target IP. For configurations where both paths to the iSCSI target travel over different networks-or-subnets 1. com. 2 Network Topology The ideal network configuration in a multipath environment is to connect each network port on your server to a different subnet. 10. X) -Connect to individual Switch Than you can have QNAP NAS Configuration NIC1 - (Subnet 172. iSCSI multipathing enables us to multipath to this type of clustered storage. Like software initiator iSCSI, the HBA ports and the storage controllerports must be on different subnets. You will be prompted for a reboot. Specific implementations can Doing port bonding is a Bad Idea with iSCSI. With native operating system support for teaming and the introduction of SMB 3. As an option, Cloud Block Store also supports different subnets. For multipath-based HA and for load balancing, multiple sessions must be manually added to declare the different paths that are available. 0/24 subnet I have 192. Port Channels for iSCSI Storage. 04 LTS 5 2. conf configuration file: The iSCSI protocol is a block storage protocol with specific dependencies on adequate response times, throu ghput, and latency. (This is handled by the iScSi initiator on servers. iSCSI-PG2 will use uplink 2. None of these devices can be on the same subnet. You can not use failover on iSCSI bound network cards. 125:3260 # iscsiadm Concepts. Plug a machine into the iSCSI network, give it a static ip address in the right range, open a web browser and browse to the ip address you entered for the SAN group. This document from VMWare goes over it in detail up to 5. Now in Windows Server 2012, no more downloads and separate -iSCSI SAN • Shared leaf-spine network topology -Software defined storage (SDS) -iSCSI SAN 1. 168. If needed, install and configure the iSCSI software initiator on the host. In this multipath configuration, the initiators and targets on one switch should be on a different subnet than the initiators and targets on the other Click add session, select enable multi-path, click advanced. 10. But, for academic thoroughness, you can provide minimal routing support in vSphere because a route look-up is done when selecting the vmknic for sending traffic. This connection can only be made through a router. 16. NIC Teaming can be configured so that if one interface fails, another can take its place. Do not use port binding when any of the following conditions exist: n Array target iSCSI ports are in a different broadcast domain and IP subnet. In normal circumstances, if you have multiple vmkernels on the same subnet, the ESXi host would simply choose one and not use both. To enable multipath I/O for an iSCSI target, assign to it multiple IP addresses from different networks using the -a option. Because of the network complexity, it's best that MPIO or MC/S is deployed by experienced network administrators. Example 1. In the second article, I will explain how to move the Oracle DB from the NFS mount point to the iSCSI mount point without changing anything in the Oracle configurations. 1 do not support routing when using the iSCSI port binding, which is a required for MPIO with EQL storage also it’s a best practice for iSCSI connectivity. For example, if four IP addresses are created and there are four simultaneous TCP connections, MPIO will send the data over all available links. To maximize bandwidth, the MPIO DSM automatically uses any available network interfaces. Isolate iSCSI network traffic from other network traffic by using VLANs or separate network equipment. You are prompted to reboot the server - this is necessary for iSCSI MPIO to be added. Array target iSCSI ports are in a different broadcast domain and IP subnet. 6 vmk3: 192. The recommendation is to have iSCSI and the service console on different subnets. Port binding should not be used when iSCSI vmkernels are in different subnets and broadcast domains. At this point there's about 10 different IPs in the mix, plus those VLANs, and a bunch of identically colored cables. 0. 11. X) - Connect to individual Switch NIC2 - ISCSI_2 (Subnet 172. With ActiveCluster, a volume exists on both arrays, so essentially the iSCSI targets on the 2nd array just look like additional paths to that volume–as far as the host knows it is not a two arrays, it just has more paths. It depends on the option you choose at the end of the tutorial (in the properties of the iSCSI Initiator -> Devices -> MPIO -> Load Balancing Policy). The targets have been discovered by the client. Note: There have been limitations in the past when using software iSCSI when the iSCSI initiator and target had to be on the same subnet. also iscsiadm -m session -P3. Equal-cost multipath (ECMP) for different subnets available through the same next-hop routes The switch supports optional load-sharing across redundant links where the network offers two, three, or four equal-cost next-hop routes for traffic to different subnets. In this article I’ll be getting in to the first point, how to configure a vSphere Distributed Switch for iSCSI multipath MPIO with multiple subnets. That way, you have additional resilience in case one of your subnets goes down (i. Routing is required to reach the iSCSI array. If you use iSCSI or NFS and the subnet is different between your ESXi hosts and your storage system, you have to modify the Virtual Storage Console for VMware vSphere preferences files. For example: Multipath iSCSI for VMware in IBM Cloud. 22. 168. To achieve that, LACP bundles several physical ports into a single logical channel. 0/24 as Allowed Hosts. At properties, click devices -> MPIO -> select Least Queue Depth as load balance policy. vmware:esx-host01-64ceae7s -A vmhba33 esxcli iscsi adapter discovery sendtarget add -a 10. EMC’s VNX TechBook has a section on iSCSI (published Jan 2015) and recommends against VMkernel Binding, instead preferring multiple subnets in a somewhat more complex design that is further debated in a few different community threads. Aside from the performance benefits that MPIO brings, it also enables redundancy in that a path may go down between the Hyper-V host and the storage system, and the virtual machine stays I configured iscsi on Linux with two independent nic, but in this way lefthand redirect session from each nic to the same storage nic: I can not configure dm-multipath, because I'm really not havin two path but only one path on the san side. 2. Therefore, the VMkernel ports that will be used 6 Group hosts together with other hosts a For cluster con gurations use the from IT 101 at Nazarbayev University In this case, the plan is to set the iSCSI initiator in the Linux and enable multipath and add PureStorage LUNs as mount points. A volume can be mapped the same way either to a Fibre Channel host, an iSCSI host, or both. Benefits of using MPIO on a Turbo NAS: - Ensures failover. First published on TECHNET on Jun 08, 2012 Windows Server 2012 comes with a complete set of PowerShell cmdlets for iSCSI. iSCSI-init is an auxiliary program for Open-iSCSI. 168. 12. ) for ISCSI multipath to work you need to setup the VMK interfaces in different network and different vlan. In the array, the target iSCSI ports are in different broadcast domains or IP subnets. This is a mandatory step to make multipathing work correctly. Windows Multipathing (MPIO) service is (as would be the case where primary data access is over FC) and that the volumes being accessed are primarily presented over the FC interfaces and already configured using the Microsoft Device Specific Module (DSM). x client. 11/24. The network subsystem can be configured to determine the path/NIC that iSCSI interfaces should use for binding. Isolate iSCSI network traffic from other network traffic by using VLANs or separate network equipment. Example. The network subsystem can be configured to determine the path/NIC that iSCSI interfaces should use for binding. I configured iscsi on Linux with two independent nic, but in this way lefthand redirect session from each nic to the same storage nic: I can not configure dm-multipath, because I'm really not havin two path but only one path on the san side. Another benefit is the ability to use alternate VMkernel networks outside of the vSphere host management network. When the VMkernel ports for software iSCSI multipathing are in different broadcast domains and IP subnets, you must not bind the VMkernel ports to the software iSCSI adapter. The following are two different configuration examples outlined. We will be separating these out for current use and later use, but we can use the different vlans for MPIO with iSCSI, and because you cannot use MPIO with NFS we can create NFS exports on different subnets to be used as VMware datastores mounted on different subnets which will allow us to use different uplinks therefore creating our own MPIO Use MPIO if you need to support different load‐balancing policies on a per‐LUN basis. 2. With port bonding, you cannot use the aggregated bandwidth, only one link at a time from point A to point B. Have you opened MPIO in windows, switched to the discovery multi-paths tab, checked the "Add support for iSCSI devices" box, added it, hit ok and rebooted the server yet? Regarding the access control list, you should always use the access control list since it's the only way different initiators are aware of eachother when connected to the target. Enabling datastore mounting across different subnets If you use iSCSI or NFS and the subnet is different between your ESX hosts and your storage system, you need to modify two settings in the Virtual Storage Console for VMware vSphere preferences files. If Multipath is enabled, then these target-specific settings will be applicable for all iSCSI sessions to this target. 0, and 5. The following diagram is an example of how the configuration should be implemented. for fault tolerance and performance enhancement, multipathing is used between the readydATA 5200 and the hyper-V servers. The performances are affected so by this behavior. 1 do not support routing when using the iSCSI port binding, which is a required for MPIO with EQL storage also it’s a best practice for iSCSI connectivity. Step 3: Click “Dynamic Discovery” and then click “Add…” to add the data ports’ IP addresses of both controllers. The doc describes binding (explicit assignment) as being technically possible but not supported (page 44-45) due to the multi-target nature of the array. Go to Features and check Multipath and then click Install, you will need to reboot. iSCSI port binding, binds an iSCSI initiator interface on a ESXi host to a vmknic and configures accordingly to allow multipathing in a situation where both vmknics are residing in the same subnet. But in this case I can use two NIC in different subnets. Trunking: The method to combine multiple network links to achieve aggregated bandwith in parallel. Link-bonding specified by IEEE’s 802. 1. 10. Go to the Discover Multi-Paths tab, select Add support for iSCSI devices and click Add. ESX for VMotion, NFS, and iSCSI you are required to have a vmkernel vNIC and for service console a service console vNIC. 62. 168. eth0 – 151. 168. Setting up iSCSI Multipath in Ubuntu Server 12. Step 2 port-profile type vethernet name Example: n1000v(config)# port-profile type vethernet VMK-port-profile n1000v(config-port-prof)# On each storage processor I have One NFS Storage server; and One ISCSI Storage Server configured with 2 IPs each in different subnets. This allows multiple iSCSI connections on multiple NICs residing on the same subnet to transmit and handle the traffic properly. Hope this helps some. Use iSCSI bindings to maintain path seperation. although it is possible to authorize multiple subnets (either for different hosts, or for different interfaces on each host). In short: Bonding works for NAS; MPIO works for SAN The Mac has two network ports on separate subnets that match two of Evo's subnets. eth10 and eth11 on SPA are tied together from the VNXe side as well as being in "PortChannel 1" Each port group should have its own active uplink. 4. Betreff: Re: [Iscsitarget-devel] Howto MPIO =09 =09 Ip routing is based on subnet and you can only have 1 active route at 1 = time. 11. For a Windows multi-pathing environment, each Unity iSCSI interface providing iSCSI LUNs for the host must have two IP addresses associated with it. • Multipathing Configuration for Software iSCSI Using Port Binding Method 2: Separate Domains This method should be used in the following scenarios: • Target iSCSI network ports are on different local networks and IP subnets. Jumbo frames. Problem 2) MPIO operates at the iSCSI protocol level. The MPIO allows you to connect to a server (for example : an iSCSI server) via multiple paths to obtain fault tolerance and/or to distribute the network load via different paths. Sorry the title is a bit of a mouthful. 131. However, it can handle multiple storage repositories across the same interface. Note or copy the iSCSI target Setting up Software iSCSI Multipathing with Distributed vSwitches with the vSphere Web Client. By combining the iSCSI target, iSCSI initiator, and storage cmdlets, you can automate pretty much all management tasks. =09 Only have 1 switch? To achieve best performance, the host should be on a local subnet with each Unity iSCSI interface that provides storage. Therefore, the VMkernel ports that will be used multipath drivers used in baremetal server implementations. On AIX host, configure 4 different IP subnets with below commands. To utilize the network bandwidth and to have better redundancy at physical layer, configure each portgroup to be in different virtual switch and configure each vmkernel portgroup for NIC Teaming. 10. By doing this, iSCSI takes a popular high-performance local storage bus and emulates it over a wide range of networks, creating a storage area network (SAN). With iscsi MPIO over different subnets, it's not routing. 4. 0 shares in Windows/Hyper-V Server 2012, it all got murkier. I have written some posts on iSCSI in the past, around setup: Setting up iSCSI with VMware ESXi and the FlashArray Configuring iSCSI CHAP in VMware with the FlashArray Another look at ESXi iSCSI Multipathing (or a Lack Thereof) These Some iSCSI targets support what's called multiple connections, so you can use a different sort of method to log in and then accomplish the multipathing using this multiple connection option. The hosts may be connecting to different individual LUNs/targets or multiple hosts may be connecting to the same target. x. 1 Dedicated storage networks Fibre Channel storage has imparted a traditional network implementation to IP-based storage. - In the array, the target iSCSI ports are in different broadcast domains or IP subnets. Each controller in Binding itself technically doesn’t “ allow multipathing”, just having multiple adapters can do that. 6) Create the iSCSI volume and attach it to iSCSI target 7) On the Ubuntu server run command to discover iSCSI MPIO on the other hand works between the hosts and iSCSI initiators and properly load balances the traffic of single flows to the different iSCSI initiators. Complete the Add Roles and Features wizard to install the MPIO feature to your Hyper-V Host/s. The tricky part was to modify the multipath-configuration, so the iSCSI-targets that went to the same physical storage were seen as the same device. 6 vmk4: 192. Once MPIO is installed open the iSCSI Initiator. In this MPIO configuration, would you use two different subnets? We have been deploying with two switches in redundant ring stacks with one subnet for iSCSI traffic and then one for the crossover link between Starwind HA members. First published on TECHNET on May 21, 2012 The iSCSI Target made its debut as a free download for Windows 2008 R2 in April 2011, since then, there were more than 60,000 downloads. We will next enable MPIO, and, then add the second path). bad switch or router). 11/24 eth2 172. 2. As a result, to achieve load balancing, an iSCSI interface connected to a Linux host must have each NIC configured on a different subnet. Best Practice: For data resiliency and performance, enable multipath on all production systems. Multipath interference is a common cause of "ghosting" in analog television broadcasts and of fading of radio waves. If you have a configuration that connects a target by using both iSCSI and FC, the MPxIO driver can provide different transports to the same Best practice configuration for different subnets. HPE recommends dedicating paths according to the protocol: For FC, dedicate each set of paths on a physical fabric or vSAN. eth2 – 10. When multiple subnets are not an option, you can still configure multiple interfaces on the same subnet for high-availability only purposes. 1. 10. In most of our iSCSI systems we use Multipath I/O, we do this by giving the iSCSI Target two NIC’s and give each NIC a IP-Address in a different subnet over a physically different network. 3. In case one of the network connections fails, the iSCSI targets will still be accessible via the other one. 100. - The VMkernel ports for iSCSI connections are in different broadcast domains, IP subnets, or vSwitches. Question for the same exact setup I have a question for the iSCSI SAN lets say your using a Dell MD3200i array and it comes with two controllers each with 4 1GB nics, my question is what network should each port be configured for? I noticed the default is configured with different subnets. 10 for port 1 on controller 0 and 192. Now for multipath to work correctly first you'll need to define two non routed subnet and map evenly each controller port to each different subnet (and maybe VLAN). Enabled MPIO driver, go to the discovery portal, and bingo - the volumes show up, and work as multi-path. For multipath-based HA and for load balancing, multiple sessions must be manually added to declare the different paths that are available. This gives me a quantity of 2 NFS Storage Servers, and 2 ISCSI storage servers. Typical iSCSI multipathing features assign multiple addresses to a single iSCSI session, which accelerates data transport. h. 1, 5. Y) - Than the iSCSI target on the NAS will be accessible from both LAN, and you will be able to use Multipath from your ESX. These two addresses should be on different subnets to ensure high availability. Two NICs were connected to the iSCSI SAN through a multipath I/O setup. Hi guys, So next week I am finally converting my old VMWare infrastructure to Proxmox and I have a question about iSCSI MPIO with our HP P2000 G3. 04 5 2. I would not do anything your asking *hardware level*. When multiple subnets are not an option, you can still configure multiple interfaces on the same subnet for high-availability only purposes. On the Windows Server 2003 box, , configure the Intel NIC’s on different network subnets (i. each interface on separate subnets) Whether or not I should use iSCSI Port Binding; So many articles on the internet, and most were wrong. If node Ethernet ports are connected to different isolated networks, then a different subnet must be used for each network. SCENARIO. Creating iSCSI LUNs and Targets. Setting up iSCSI Multipath in Ubuntu Server 14. I have the san operating under two different ip ranges 192. When configuring MPIO, make sure that the IP addresses on the interfaces are configured to be on separate subnets with non-overlapping netmasks, or configure active/passive iSCSI arrays that required support. On the Assign Iscsi target page, ensure that the New Iscsi target radio button is selected, and then click Next. Enabling datastore mounting across different subnets If you use iSCSI or NFS and the subnet is different between your ESXi hosts and your storage system, you have to modify two settings in the Virtual Storage Console for VMware vSphere preferences files. 8. Before enabling DM-Multipath on the client, there is no /etc/multipath. Please note that only x86-based Turbo NAS support MPIO. It, however, does not matter if I do it with separate subnets or not. Log into Storage Controller A and type the following commands, iscsi nodename. 2) Install Microsoft Initiator 2. It's recommended to use MPIO with separate networks (or different subnets) with multiple network cards to be installed on the iSCSI Initiator and Target. My freenas just has 5 nics all with different IPS, I tried setting them up with different subnets, but that doesn't seem to work with ESXI I have MPIO setup on the ESXI box, but I'm not seeing the performance I'm expecting, about 50mb read and write. Configure two to four Open-iSCSI interfaces through the host console. 20. From host side, it can see two iSCSI targets on each controller. 168. Problem 2) 3-Time to correctly configure iSCSI and MultiPath on cluster VMs in order to make sure that settings are supported and optimal, do this procedure on all VMs that are part of the failover cluster: Open ISCSI Initiator Properties and head over to Discovery then add the vmk1 IP of all ESXi servers that are part of the vSAN cluster: Little or no investment in new network technology is needed to start using an iSCSI SAN. 125:3260 # iscsiadm -m discovery -t st -p 192. com. For instance: 192. Windows Server 2012 using MPIO QNAP provides you with what others cannot! In addition to the other available features on your Turbo NAS, MPIO (Multipath Input Output) enables you to have multiple paths to reach an iSCSI target. The best way to set up an iSCSI network for vSphere is to use vmkernel port binding. iSCSI Subnets and Routing Recommendations VMware vSphere 4. 168. Note: It is strongly recommended to use MPIO with separate networks (or different subnets) with multiple network interfaces on the iSCSI Initiator and Target. Launch the MPIO utility by typing mpiocpl at a run menu. 3 for iSCSI communication. After the MPIO feature is installed, configure MPIO by opening Server Manager, Tools, then MPIO. Some arrays still require an administrator to add additional paths manually. To use MPIO while we connect an iSCSI target via 2 paths, select iSCSI LUN while we connect a Target, click Connect, and check the Enable multi-path option. Another advantage of multipathing is the increased throughput by way of load balancing. Each iSCSI interface is used to establish a separate path. Config the first path through one of you network interfaces: # service iscsid start # chkconfig iscsid on # iscsiadm -m discovery -t st -p -P 1 # iscsiadm -m discovery -t st -p -l 2. Good that you found your answer. In 5. At this point, only one of the SAN network interfaces is enabled which is on the iSCSI network. Beyond that, ensure your cabling is good, if you're using routed storage, meaning different subnets per NIC, then ensure you have as few hops as possible to targets. With different subnets we can have independent connections from different vmkernel portgroups. e. Click the Discovery tab and then click Discovery Portal (note you will need to add both targets for MPIO) Here we enter the IP of the QNAP NIC which will be the first path so 10. The only *hardware level* things I would recommend is a battery backed raid card, if you need one. The iSCSI multipath feature sets up multiple routes between a server and its storage devices for maintaining a constant connection and balancing the traffic load. a. 1 iSCSI settings for dm-multipath ===== When using dm-multipath, the iSCSI timers should be set so that commands: are quickly failed to the dm-multipath layer. 10. To enable MPIO: In the Windows server, open MPIO. NFS connections can be done via a bond, so in that case you'd also have used three interfaces. Click OK. Usage of MPIO is recommended for experienced network administrators only. 5 ; When not to Bind. Normally, these networks are discrete and maintained on separate subnets. Inside globalSAN, we added a Portal/Group using one of the Evo IP addresses. The common use case for this kind of storage system is for the shared storage between multiple servers. The iscsi-portal now knows the name of the initiator, for example iqn. Perform any one of the following: We are in the process of setting up a new iscsi based on FreeBSD, ZFS and istgt(1). 1. I think they need to be on different subnets to be considered different paths as otherwise the routing will always use one of them anyway. This is suggested because MCS can only define policies on a per‐session basis, while MPIO can define policies on a per‐LUN basis. Each Ethernet interface must be on a separate subnet. An example is shown below: Notice how the individual NICs are configured to be in different subnets and the corresponding target port IP addresses. x subnet is used for the Synchronization traffic. I have written some posts on iSCSI in the past, around setup: Setting up iSCSI with VMware ESXi and the FlashArray Configuring iSCSI CHAP in VMware with the FlashArray Another look at ESXi iSCSI Multipathing (or a Lack Thereof) These n The single switch configuration is not appropriate for iSER because iSER does not support NIC teaming. Trending posts and videos related to Vsan Direct! It’s strongly recommended to use MPIO with separate networks (or different subnets) – with multiple network cards to be installed on the iSCSI Initiator and Target. Two NICs are in different subnets, and I add two portals. 0/24) and use the multipath It is strongly recommended to use MPIO with separate networks (or different subnets) with multiple network interfaces on the iSCSI Initiator and Target. eth3 – 10. In the IPv4 Address: field enter the iSCSI address for the server corresponding to the iSCSI-A-VLAN subnet. Previously users needed to use the command-line to get an optimal multi-path configuration with Software iSCSI. Environment: Oracle 12c R2; Linux CentOS v7 The best 'Vsan Direct' images and discussions of April 2021. 168. 168. This method is not specific to any underlying transport and is the standard way to achieve multipath access to iSCSI, Fibre Channel, and even parallel and serial SCSI targets. bad switch or router). 10. Select the Discover Multi-Paths tab, check the Add support for iSCSI devices and select OK. The best-practice recommendation for failover is to use two switches; however, even if you do notconfigure two switches, the physical networks associated with the HBA ports being multipathedmust be on different subnets. i. 6. esxcli iscsi adapter set --name iqn. 16. You can find information on the second point here, when to use iSCSI Port Binding Software iSCSI Multipathing. The VMkernel ports for iSCSI connections are in different broadcast domains, IP subnets, or vSwitches. In essence, iSCSI allows two hosts to negotiate and then exchange SCSI commands using Internet Protocol (IP) networks. 63. The network interfaces can reside on the same subnet or separate subnets. For information about configuring multipathing for software iSCSI, see Setting Up Network for iSCSI and iSER. The dedicated storage network has a proven design that provides performance, predictability, and manageability to storage Step 2: A new software iSCSI adapter will be added to the Storage Adapter list. The QES only allows fixed IP address configuration for Ethernet ports designated for data services. If Multipath is enabled, then these target-specific settings will be applicable for all iSCSI sessions to this target. On the same screen, for binding the port groups to the software iSCSI adapter as well as active vmknic-based multipathing for iSCSI software, select the Network Configuration tab, click Add, and then select the iSCSI01 and iSCSI02 port groups. This often happens when the SAN’s adapters are teamed, won’t allow their adapters to participate on separate subnets, or the configuring administrator inadvertently connects the initiator to the wrong target. The 10g ports are used for iScSi connectivity to the hyper-V servers. If you do not modify the preferences file, then datastore provisioning fails because Virtual Storage Console (VSC) cannot mount the datastore. 1 Environments Using iSCSI Host Interfaces VMware environments often use the iSCSI protocol to connect ESXi hosts to a multivendor storage MPIO works between hosts and initiators on FC or iSCSI. For your iSCSI Target server, it could be Windows Server 2016 or 2019, physical or virtual, running on Hyper-V, VMware, or an alternative appliance of your choice, such as a dedicated It is perfectly okay to configure 4 iSCSI NICs per host server across the 4 iSCSI subnets (which I have done in the past. If your target has only one network portal, you can create multiple paths to the target by adding multiple VMkernel ports on your ESXi host and binding them to the iSCSI initiator. for 192. 0, VMware has added a new UI interface to make it much easier to configure multipathing for Software iSCSI. If you plan to use multiple network adapters for iSCSI communication, you should separate them into their own subnets, set up virtual IP addresses, and then implement MPIO. srvrux30. When you configure MPIO DSM, consider restricting its access to subnets dedicated to iSCSI data traffic. 16. When setting up multiple paths on the iSCSI network, the iSCSI network typically has multiple physically disjoint segments, such as a BladeCenter® with two switches dedicated to iSCSI traffic. 1, 5. You can run multipath -ll. The initiator has redundant network connections to the target. SLES 11 SP3 server with 5 NICS (1 on public network, 3 on private network dedicated to iscsi). It is also common for an iSCSI network to be deployed on fast Ethernet such as 10 Gigabit (or more) optimized performance and IOPS. The QES only allows fixed IP address configuration for Ethernet ports designated for data services. The iSCSI stack (including the target) on the Celerra is done above the Celerra filesystem, and is different than the iSCSI stack on the CLARiiON (getting the best of both) Over time, these will merge, but move forward with confidence. On the Specify iSCSI virtual disk name page, in the Name text box, type CSVDISK1, and then click Next. Both are aimed at providing higher throughput when one connection can’t handle the task. 61. On the Specify Iscsi virtual disk size page, in the Size text box, type 10, ensure that GB is selected, and then click Next. See Step 6 for more information about If everyone think for a different name than backupportal, iscsi-multipath-backuptp branch 2 times, most recently from c625314 to 890c780 Feb 2, 2017. * as the node nics correspond under the same subnets. Each Ethernet interface must be on a separate subnet. It can be called either from INITRD or in kickstart pre-install scripts to help with initialization and attaching iSCSI boot LUN. Here is a comparison of two technologies with similar task but different methods of accomplishing it – Link Aggregation Control Protocol (LACP) and Multipath I/O (MPIO). 10. in the VMware iSCSI SAN Configuration Guide. The following guidelines apply to iSCSI networks: In the diagram, multiple hosts are, indeed, connecting to a single iSCSI array. Inorder to have multipath between initiator and target, make sure we have different IP subnets. 2 and 192. 1. 11 for port 1 on controller 1 and so on. All iSCSI targets should be on the same subnet as the iSCSI vmkernels; All the vmkernels must me on the same subnet and broadcast domain; iSCSI port binding only supports routing in vSphere 6. I have two identical servers for ESX but only one is set up right now. 3ad and trunking in iSCSI ERL-2 are different implementations. 5. while deploying a cluster, configure MPIO on all nodes. 2. Objective: To provide a quick overview of the steps needed to bind different NICS to iSCSI ifaces and use those ifaces to setup multipathing. 2. iSCSI port binding, binds an iSCSI initiator interface on a ESXi host to a vmknic and configures accordingly to allow multipathing in a situation where both vmknics are residing in the same subnet. 192. For example: If we have one physical network adapter, we need one VMkernel port on a virtual switch, however, If we have two or more physical network adapters for iSCSI, we can use these adapters for host-based multipathing. 100. You should definitely use two different subnets for MPIO. • VMkernel ports used for iSCSI are on different vSwitches. 2 Network Topology The ideal network configuration in a multipath environment is to connect each network port on your server to a different subnet. Some customers have their two arrays in different datacenters, and also different subnets (no stretched layer 2). I have written some posts on iSCSI in the past, around setup: Setting up iSCSI with VMware ESXi and the FlashArray Configuring iSCSI CHAP in VMware with the FlashArray Another look at ESXi iSCSI Multipathing (or a Lack Thereof) These Configure network interfaces on each node to make sure that Synchronization and iSCSI/StarWind heartbeat interfaces are in different subnets and connected according to the network diagram above. SoftLayer iSCSI storage is a great platform for running a clustered OS and file system. In case it helps your answer, my setup is currently a SAN with 4 NICs teamed to a dedicated iscsi only switch, and 2 teamed NICs to our production network The quad port teamed NIC has 2 IPs assigned to the team, each of different subnets. An iSCSI session is active between the target and the initiator. Two controllers can access the same volume intenally, so MPIO will merge the paths. 0/24 and 192. 10. 10/24 up 5) Set up both NICs eth1 and eth2 on DSS eth1 172. 04 with MPIO selected On Windows 2003 client, install storport update KB932755 In Microsoft Initiator, on the Discovery tab, create two iSCSI targets – one for each network card iSCSI (Internet Small Computer System Interface): iSCSI is a transport layer protocol that describes how Small Computer System Interface ( SCSI ) packets should be transported over a TCP/IP network. Frank Without iSCSI multipathing, this type of storage would have one path only between the vSphere host and each volume. I've tried configuring SA0 and SB0 to the same IP, but SB0 fails saying the IP address is in use. We have discovered that instead of this SVM responding to an iSCSI sendtargets request with just the 6 IPs from the mapped portset, it will respond with all 12 IPs from both portsets. 5, the software iSCSI initiator and target can be on different subnets, but not when using software iSCSI port binding. After that, we selected each target it found, and added an additional path on the right side of the preference pane. Note that multipathing requires different subnets between two paths. This is suggested because MCS can only define policies on a per‐session basis, while MPIO can define policies on a per‐LUN basis. For the latest maximum configuration support information, see the following Web sites: Here the use case is different: we have multipath using two physical devices on host, both configured for the same subnet, and two iSCSI connections to the same target IP, each connection using its own host physical device: eth1 (192. g. With different subnets, you can use the "full dual speed" (ie 2x1Gbps or 2x10Gbps) between point A and B. With vSphere 6. 168. Then click Advanced and bind different initiator IP addresses to different target IP addresses. 70. Using either MPIO or MC/S requires at least two network ports on both the Initiator and the Storage Array; it is also strongly recommended to use the network cards within separate networks (or different subnets). On another note (which might prove useful to your setups in the future), it is possible to achieve 2Gbps with two adapters on the source and bonded adapter on the NAS (so 2 → 1) when using the MPIO iSCSI Initiator that comes with Server 2008. uk The only point I would like to add is that if the SAN has dual controllers, it should have separate VLANs and subnets for each iSCSI port on and individual controller to optimize MPIO utilization. 1. The storage is a dual controller subsystem. 2. iSCSI Multipathing should be configured using IP's on different network subnets/vlans to ensure proper communication of the paths. 225 Array-Based Failover with iSCSI Some iSCSI storage systems manage path use of their ports automatically and transparently to ESXi. The UI allows one to select different network interfaces for iSCSI … Continued The only differnce between the IPs being on one subnet or multiple subnets will be the number of iSCSI sessions / paths established to the iSCSI target. Login with the “grpadmin” account when prompted. redhat:swiscsi. Additionally, In this test environment, I had kept them on the same subnet (192. 168. With active/passive arrays, the vSphere host storage stack was required to recognize each of the portals as different paths (targets) to effectively do multipath failovers. The path policy defaults to round robin and - can be tuned to force alternate path selections on a smaller number of I/O requests. There are two typical network configurations: The simplest topology is to place all Cloud Block Store interfaces (system, iSCSI, management, replication) onto a single subnet. 155. If your iSCSI storage network is on a different subnet AND you iSCSI Multipathing vmkNICs are on the same subnet as the gateway to that network, routing to the storage works. Host-Based Path Failover IP network hardware iSCSI host 1 SP iSCSI storage HBA2 HBA1 software iSCSI host 2 NIC2 NIC1 software adapter Hardware iSCSI and Failover With hardware iSCSI, the host typically has two or more hardware iSCSI adapters. That was the first step to make it available for everyone. 130. The iSCSI protocol does not prohibit the routing of iSCSI traffic, as long as the network infrastructure can provide sufficiently high throughput and low latency. Proper SCSI MPIO (whether iSCSI, FC, FCoE, or some other transport) you should be adding every target to every initiator. But if you have Multiple Adapters/VMkernel ports for ISCSI used in the SAME subnet/broadcast domain, it will allow multiple paths to the ISCSI array that broadcasts one single IP Address. please make sure that each, iSCSI server and client, have two working network interfaces. Multipathing generally requires different subnets, though different hosts can use the same two subnets just with unique IP addresses on each. This one’s easy: don’t do it. 6 vmk2: 192. The following is exactly what iscsi-init does in case of two boot scenarios. 55. If it's just a lab, you can ignore this because it is just a warning. Configuration The classic way to do multipathing is to insert a separate multipathing layer into the storage stack. 9. The P2000 FC/iSCSI combo G3 MSA (for iSCSI traffic) and P2000 G3 10GbE iSCSI MSA use port 0 of each controller as one failover pair, and port 1 of each controller as a second failover pair. All cabling and, in case of iSCSI, subnet configurations must match the corresponding NICs on each host. The best practice recommendations for configuring iSCSI are to use two switches and configure them to be on different subnets. For iSCSI, use separate, private subnets that are dedicated to iSCSI connectivity. 2. So the general rule of thumb is: One subnet, iSCSI port binding is the way to go! Two or more subnets, do not use iSCSI Port Binding! It’s just not needed since all vmknics are residing on different subnets. 1. 16. SInce the MD32xxxi arrays have two Raid controllers not all of the paths to the iSCSI target will show Active. Now please configure on server both network adapters to work in different subnets: for example: - iSCSI-HA cannot take multiple instances of the floating IP and interface parameters. An example is shown as follows. You do not want to mix the same subnet disjointed on two different physical switches, as the iscsi won't know about this and you'll get into a world of hurt fast. different subnets You may also configure static routes when initiators and targets are in different subnets All bound vmkernel ports in one portals in another subnet (N2) Use static routing when using different subnets With separate gateways per VMkernel, you use port binding to reach targets in different subnet Using software level iscsi can use normal nics, supports mpio, and you can even use jumboframes. 16. For example, if portals and NICs are set up on different subnets, then it is not necessary to manually configure iSCSI interfaces for binding. Do the same for your environment, ensuring each port group intended for iSCSI uses just one uplink and it is uniquely used by that port group (in other words, it is not set to active for another port group also intended for iSCSI). If you are using iSCSI or Fiber Channel you use MPIO (Multipath-IO) to use multiple available paths to the storage. Setting up Software iSCSI Multipathing with Distributed vSwitches with the vSphere Web Client. You should not use network adapter teaming with Microsoft iSCSI Software Target 3. One of the SVMs in our 6-node cluster has 2 portsets on different subnets defined and our clients only have network access to the IPs in one portset or the other. For a Windows multi-pathing environment, each Unity iSCSI interface providing iSCSI LUNs for the host must have two IP addresses associated with it. If y By spreading the load between multiple Dell Compellent Target iSCSI bottlenecks can be avoided while providing network adapter, subnet, and switch redundancy. Setup Virtual Networking on ESXi Server for iSCSI Connection To achieve best performance, the host should be on a local subnet with each Unity iSCSI interface that provides storage. 1998-01. 10. However, you can configure node Ethernet ports in different I/O groups to use different subnets and different gateways. A problem arises when iSCSI initiators (clients) connect to iSCSI targets (hosts) that are on different subnets. iscsi multipath different subnets