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Virtualization: How to Use iSCSI Targets on VMware ESXi Server with Multipath Support?
Last Updated 4 years ago


Failover and load balancing configuration is crucial when deploying virtual storage solution in your IT environment to achieve optimal resource utilization, maximize throughput, minimize response time, and avoid overload. By using multipath iSCSI connection, you may deliver a high quality and reliable storage service with failover and load balancing capability and it is also one of the best practices for virtualization environment. All of the Synology NAS with 2 or more network interfaces are equipped with multipath support on iSCSI Target to help you to deploy failover and load balancing configuration.

This article will guide you the steps of using iSCSI Targets on VMware ESXi server with multipath support.

1. Before You Start

This article assumes that you have done the following tasks for your Synology NAS:
  • Hardware installation for Synology NAS.
  • Software installation for Synology DiskStation Manager (DSM, web-based operating system of Synology NAS).
  • Creating iSCSI LUNs and Targets.
  • Enabled multiple sessions support on your iSCSI Targets.
Refer to Quick Installation Guide for more information about hardware and software installation. You can also see Synology NAS User's Guide (available at Synology's Download Center) for a general idea about topics related to this article.


  • It is strongly recommended to use MPIO with separate networks (or different subnets) with multiple network interfaces on the iSCSI Initiator and Target.
  • MPIO is only available on the Synology NAS with two or more network ports.

2. Setup Virtual Networking on ESXi Server for iSCSI Connection

This section will guide the administrator in setting up virtual networking on the ESXi server for iSCSI connection.
  1. Open the vSphere Client and proceed to Configuration, Networking and click Add Networking.
  2. Select VMKernel and click Next.
  3. Create a new network switch and select a NIC located on another subnet.
  4. Enter a name for this new network and click Next.
  5. Select Obtain IP settings automatically and click Next.
  6. Confirm all the settings and click Finish to complete the setup.

3. Connect iSCSI Target on the ESXi Server with Multipath

This section will guide the administrator to connect iSCSI Targets on the Synology NAS to the ESXi server with multipath support.
  1. Within the Configuration tab, click on Storage Adapters, select the iSCSI Software Adapter and click Properties.
  2. In this example, the iSCSI Initiator is disabled. Click Configure to configure the settings of the iSCSI Initiator.
  3. Make sure the iSCSI Initiator is Enabled.
  4. Once the iSCSI Initiator is enabled, click on Dynamic Discovery.
  5. Click Add and enter the primary IP Address of the Synology NAS.
  6. Confirm to rescan the Host Bus Adapter.
  7. In Paths, the iSCSI Initiator has detected the target on the Synology NAS.
  8. Right click on the Target and click Manage Paths.
  9. Select Round Robin (VMware). Note that within the path management, that the ESXi server is using two paths (via two subnets) to connect to the same iSCSI Target.

If you want to use Multipath I/O (MPIO) for the iSCSI targets on your Synology NAS, remember to do the following first:

  1. Go to Storage Manager > iSCSI Target.
  2. Find the desired iSCSI target, and click Edit > Advanced.
  3. Tick Allow multiple sessions from one or more iSCSI initiators.
  4. Click OK.


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