Yesterday a customer called me that one of the VMware ESX hosts is missing 1 datastore (LUN). The other VMware ESX hosts in the cluster had no problems with the datastore. Looked in the NetApp filer to see the presentation of the LUN, everything was okay.
After investing the log files on the VMware ESX host i found the following message:
Jan 22 12:39:34 boz101 vmkernel: 152:21:01:58.702 cpu4:1040)ALERT: LVM: 4476: vml.020003000060a980004335434b464a4b77554e59744c554e202020:1 may be snapshot: disabling access. See resignaturing section in SAN config guide.
It seems that the VMFS volume has been detected with a different LUN ID. The LUN ID is stored in the LVM header of the volume. When the LUN ID changes you need to enable resignature option to see the datastore again.
In the evening we powered all VMs on that LUN down. On the host that was missing the datastore, I enabled the resignaturing option by:
– Go to the configuration tab of the VMware ESX host and select Advanced settings
– Click on LVM, and changed the