Network quality of iSCSI storage is crucial when deploying a VMware environment. To ensure the stability and performance of your Synology iSCSI storage, we recommend using two or more dedicated physical network interfaces for the iSCSI traffic between your VMware host and Synology NAS. To achieve load balancing and high availability with multiple network ports, it is important to configure port binding for iSCSI Multipath I/O (MPIO).

This article guides you through configuring port binding and MPIO on VMware for Synology NAS.

• iSCSI Initiator:
  • An iSCSI host bust adapter (HBA) has been used.
• Synology NAS:
  • All VMkernel ports used for iSCSI and Synology NAS ports connected to the same local network with the same IP subnet.
  • All VMkernel ports are connected to the same vSwitch.
• SAN Manager:
  • iSCSI LUNs and Targets have been created.
  • Allow multiple sessions from one or more iSCSI initiators has been selected (configurable at SAN Manager > iSCSI > Edit > Advanced).

Assign one active network adapter per port group

This section will guide the administrator to assign one active network adapter (vmnic) to each port group on VMware vSphere Client 6.0. The administrator has to create multiple port groups for iSCSI (iSCSI-PG-A, iSCSI-PG-B) beforehand.

1. In the host Manage tab, click Networking > Virtual Switches, and select the vSwitch that you want to edit from the list.
2. On the vSwitch diagram, click on a port group and then click the "pencil" icon to edit it.
   
3. On the Edit Settings wizard, click Teaming and failover.
4. Check Override under Failover order.
5. Keep only one physical adapter under Active adapters. Select all the other adapters and click the move down arrow to move them to Unused adapters.
   
6. Repeat steps 2-5 for the other iSCSI VMkernel ports to ensure that each VMkernel port has its own unique active adapter. The final configuration should look similar to the diagram below.
   

Configure port binding

This section will guide the administrator to configure port binding on VMware vSphere Client 6.0.

1. In the host Manage tab, click Storage > Storage Adapters.
2. Under Adapter Details, click Network Port Binding and then click the green add button.
   
3. Select the port groups that you want to bind. Click OK.
   
4. Return to the Storage Adapters tab. Under Adapter Details, click Targets > Static Discovery > Add.
   
5. Enter the iSCSI target's information to add the target.
   

Locate iSCSI LUN on VMware vSphere Client

This section will guide the administrator to locate the Synology iSCSI LUN on VMware vSphere Client 6.0.

1. In the host Manage tab, click Storage > Storage Devices, and select the iSCSI LUN from the list.
2. Click the Properties tab, and then clickEdit Multipathing Policies under Multipathing Policies.
   
3. Change the path selection policy from Most Recently Used to Round Robin.