Software iSCSI port binding is the process of creating multiple paths between iSCSI adapters and an iSCSI Storage target. By default, ESXi does not setup multipathing for iSCSI adapters. As a result, all targets are accessible by only a single path.
A VMkernel port must be configured on the same network as the storage device to use the software iSCSI initiator. The initiator will use the first network adapter port it finds that can see the storage device and use it exclusively for transport. This means that just having multiple adapter ports is not enough to balance storage workloads. However, you can achieve load balancing by configuring multiple VMkernel ports and binding them to multiple adapter ports.
The next step in configuring iSCSI and port binding is to create the number of desired VMkernel ports and ensure that the same number of network adapter ports are available and can see the iSCSI storage. When this is done, a 1:1 relationship must be established between each VMkernel port and the corresponding network adapter port.
I assume you already knew the configuration of ISCSI Storage. ISCSI multipathing configuration has only three steps process.
- Define atleast two VMkernel Port (each has its separate network adaptor, if you have multiple then make sure one is active and other are unused).
- Add the Software adaptor
- Configure the Network Port binding.
Step 1: Define vKernel Adaptor.
To add a VMkernel port. Go to ESXi host -> Manage -> Network -> VMKernel Adapters -> Click Glob sign with “+” as highlighted below -> Click “Next”
Next choose the Connection type -> Click “Next”
Select New Standard Switch-> Click “Next”
Click on Green “+” Sign to assign the Physical Adapter. I reserved “vmnic5” for first vKernel port.
Define the vKernel Port Label -> Click “Next”
Set the IP address for ISCSI vKernel port -> Click “Finish”
Run the same vKernel Adapter wizard again and define the 2nd vKernel port for ISCSI Multipathing. This time assign Network adapter “vmnic4” and set the IP address. Below is the final picture.
Step 2: Add software adapter.
In my case I already added the software adapter. If this was not available in you environment. Then you click on “+” sign and add the software adapter as highlighted.
When you try to add new software adapter. Then following popup will appear choose the default and click “OK”. In my case I already performed this step.
Step 3: Network Port binding.
Select you software adapter -> Network port Binding -> Click “+”
Select your First vKernel adapter for ISCSI Port binding-> Click “OK”
Similarly add the 2nd vKernel adapter -> Click “OK”
If you find the rescan warning message. Make sure to rescan the storage adapters than verify both vKernel adapters are bindid and in “active” state.
Similarly, if you go to the “Path” tab in ISCSI Software adapter then you will see there are two paths for every LUN are available as highlighted.
vSphere Classic Client View:
See both vKernel adapter are complaint and active
Now if you go to the properties of any ISCSI datastore in this ESXi host -> Click “Manage Path”
Here you can see it has two paths. Both are active and also you can manage his multipath policy.