One of 3 Equallogic members went offline yesterday. In a trial to fix we turned off the equallogic using physical button. I know now that this was a bad idea. From the groups CLI using command show recentevents we found this before the problems started:

953885:816846:XXX-hostname-box3:MgmtExec: 4-Feb-2020 16:35:42.994882:targetAttr.cc:84
6:INFO:7.2.48:iSCSI login to target '10.XXX.XXX.15:3260, iqn.2001-05.com.equallo
gic:0-fe83b6-2d5b9c1e8-3e1baaec83e56ba0-ds-volume-XXX01' from initiator '10.1
10.202.31:38087, iqn.1998-01.com.vmware:esx1-6cbfea68' successful using
Jumbo Frames.
NOTE: More than one initiator is now logged in to the target.

It appeared multiple times for multiple different volumes. And few seconds later this:

954087:816945:XXX-hostname-box3:MgmtExec: 4-Feb-2020 16:36:41.764981:targetAttr.cc:97
4:INFO:7.2.15:iSCSI session to target '10.XXX.XXX.41:3260, iqn.2001-05.com.equal
logic:0-fe83b6-143cac2e8-eafe2b6955958bfd-ds-volume-XXX03' from initiator '
10.110.202.39:52824, iqn.1998-01.com.vmware:esx4-61a7a508' was closed.
iSCSI initiator connection failure.
Connection was closed by peer.

Our Setup:

4x m630 blades in M1000 chassis, 2 MXL switches.
2x n4032F switches
3x Equallogix PS6210, v9.1.4 (24x 900G 10K SAS)

3 HDDs in 1 of the equallogix boxes have been replaced with 1.2 TB 10K SAS drives by Dell (I assume 900G are not available anymore). I'm writing here because 2 of the Equallogic boxes warranty and support expired in January 2020. So only 1 of them is still covered. The offline box is not under warranty anymore.

CLI on the box which seems offline from the group reads this:
The storage array is still initializing. Limited commands will be available until the initialization is complete. Please try again later.

CLI> su exec 'raidtool'
You are running a support command, which is normally restricted to PS Series Tec
hnical Support personnel. Do not use a support command without instruction from
Technical Support.
Driver Status: *Admin Intervention Requested*
RAID LUN 0 Ok.
raid status unrecoverable.
12 Drives (0,2,4,6,8,1,3,5,7,9,10,11)
RAID 6 (64KB sectPerSU)
Capacity 8,641,743,421,440 bytes
RAID LUN 1 Ok.
raid status unrecoverable.
11 Drives (12,13,14,15,16,17,18,19,20,21,22)
RAID 6 (64KB sectPerSU)
Capacity 7,777,569,079,296 bytes
Available Drives List: 23