Max no. software iSCSI Initiators per ESX 3.5.0 host?

[dellboy]

Hi

What is the maximum number of Software iSCSI Initiators an ESX 3.5 host can have?

The latest Configuration Maximums gude says 2 x Hardware iSCSI Intiators per host but doesn't mention anything for the Software iSCSI Initator. Does the same apply?

[weinstein5 · Accepted solution]

No - your can only have one software iSCSI initiator - only one instance can run in the vmkernel -

[dellboy]

Damn, so I guess there's no point dedicating lots of physical NICs to software iSCSI - I had four to play with. Now I'll only use two.

Thanks for the quick response

[kjb007]

There isn't a 1:1 between iSCSI sw initiator and NIC. Your iSCSI initiator is using the vmkernel port on a vSwitch to handle the communication between ESX and iSCSI san. You can add multiple NICs in a team to that portgroup that the vmkernel lives on. Then, that should give you multiple paths to your iSCSI storage, and you should be able to do load balancing, to a degree.

-KjB

[dellboy]

Yeah, the initial aim was to use 802.3ad Link Aggregation to create two bonded pairs of GigE NIC (one bonded pair per physical switch) for redundancy and speed

However given this limitation of the Software iSCSI Initiator; along with the fact that the Software iSCSI Initiator only uses one pNIC in a bonded pair; and the 802.3ad requirement for pNICS to be patched into the same physical switch or stack, I lose the benefits of redundant paths across physical swiches AND 2GB pipe!

Instead, we'll just add two GigE pNICs to the iSCSI vSwitch; patch them into seperate physical switches, and change the Load Balancing policy back to the default Route based on Originating Port ID.

[kjb007]

You will have to manually do the multipathing config here, as using either load balancing algorithm (port ID/IP hash) requires that there be multiple source and destination IP/MACs. Since you will have the vmkernel port initiate, and the iSCSI target be on the other side, with 1 IP address, there will only be 1 SRC-DST combination.

Configure 2 pNICs, and set the target, and then you can go into the datastore configuration once it is setup, and round-robin your LUNs over the 2 paths (NICs) to get additional throughput.

-KjB

[matuscak]

Keep in mind that you can still run software iSCSI initiators inside the VMs. We've got the service console on one nic and then the VM based initiators connected to a different nic. We do the initator inside the VM for our SQL server and large file server storage.