iSCSI Problem

[nsusa]

I do have some problems with my iSCSI setup. We are doing failover testing and one of the iSCSI connections will not show the storage at all. Our setup (Dell 2950 / MD3000i) is as follows:

4 NICs dedicated to iSCSI

2 non-routable VLans

4 V-Switches - 2 on each non-routable VLan - each V-Switch has 1 VMNIC assigned.

Due to limitations all these connections are on the same physical switch. If I remove 3 NICs at a time I rescan and do see storage. I rotate one NIC out and another in onto its assigned V-Switch, rescan and I see storage. However, on one of the NICs I do not see iSCSI storage - just local. If I move that VMNIC to the other V-Switch that is on the same VLan I do see storage. If I delete the "working" switch and move the VMNIC back to the remaining V-Switch on that VLan I do see storage.

Any ideas why this would happen and how to fix it?

[ephillipsme]

If you are using the software Iscsi you can only use a single path and single vswitch. To can some redundancy with this the ISCSI vmkernal nic ican be on a vswitch with mutlipl vmnics and set the load balancing to failover, this will allow for you multiptathing across the single vswitch.

~E

[nsusa]

I was under the impression that NIC teaming is a No-No for iSCSI connections - at least in the 3.5 world. Also, this used to work in 3.5 for me, but now on vSphere ....

[ephillipsme]

NIC teaming can be a no-no for iSCSI. if you set the vswitch load balancing to failover or choose the vmvics for failover order you should be ok. The issues is if you have ip hash or other NIC teaming software iSCSI is not able to handle the multiple paths. AS far as esx 3.5 not sure as multi pathing and single vmkernal were also limitations in that version.

~E

[ChrisJ615]

Ding Ding! MPIO, sir.