In the “Multivendor post to iSCSI” article by Chad Sakac and others(Netapp, EMC, Dell, HP, VMware) a new multi-pathing method for iSCSI on the next version of ESX(vSphere) had already been revealed. Read the full article for in depth information on how this works in the current version and how it will work in the next version. I guess the following section sums it:
Now, this behavior will be changing in the next major VMware release. Among other improvements, the iSCSI initiator will be able to use multiple iSCSI sessions (hence multiple TCP connections).
I was wondering how to set this up and it’s actually quite easy. You need to follow the normal guidelines for configuring iSCSI. But instead of binding two nics to one VMkernel you create two(or more) VMkernels with a 1:1 connection to a nic. Make sure that the VMkernels only have 1 active nic. All other nics must be moved down to “Unused Adapters”. Within vCenter it will turn up like this:
After you created your VMkernels and bound them to a specific nic you would need to add them to your Software iSCSI initiator:
esxcli swiscsi nic add -n vmk0 -d vmhba35
esxcli swiscsi nic add -n vmk1 -d vmhba35
esxcli swiscsi nic list -d vmhba35 (this command is only to verify the changes)
If you check the vSphere client you will notice that you’ve got two paths to your iSCSI targets. I made a screenshot of my Test Environment:
And the outcome in ESXTOP(s 2 n), as you can see two VMkernel ports with traffic:
There’s a whole lot more you can do with esxcli by the way, but it’s too much to put into this article. The whole architecture changed and I will dive into that tomorrow.