iSCSI SAN Storage Not Connecting

[callmemonks]

I've set up a Fujitsu DX100 S3 SAN with four iSCSI connections. As far as I know it's been correctly set up and I have tested this by connecting the SAN to a server which has correctly mounted the volumes.

My issue is trying to connect this SAN to our VMWare environment running vCentre 5.0.

The SAN appears in the Static Discovery tab in the iSCSI Storage Adaptor properties when entering the IP addresses of the iSCSI connections in the Dynamic Discovery tab (including the correct IQN names for the connections).

However, the problems start when a rescan of the storage adaptor is performed. The SAN does not show up on the devices section.

After checking the log files I noticed that in the vmkernel.log file there is an entry for when the SAN is bought ONLINE but soon after there is another entry (a warning) which reads:

"...iSCSI connection is being marked "OFFLINE" (Event: 4)"

Does anyone have any ideas as to what's going on and how I can resolve this issue and get the SAN connected to our VMWare environment?

[vembutech1]

There might be network connectivity from ESXi host to iSCSI array or misconfiguration of MTU settings on vswitch or vmnics. Does the issue happens only on a particular ESXi host ?. Also check the same LUN connects to a iSCSI connector on a physical machine.

[callmemonks]

The issue happens on all four ESX hosts we have. Also, yes the same LUNs connect just fine to a physical server via the iSCSI initiator.

We have other iSCSI connected SAN devices (HP P2000 and a HP P45) connected to the ESX hosts that are working fine so I'm guessing all the vswitch and vmnic settings are correct. Those SANs are also using between 2-4 iSCSI connections.