After patching an ESX server, a LUN is suddenly missing

After an upgrade you might in some rare occations lose a LUN. There are no obvious error messages in the logs, but on the console of the ESX server you will typically see a message like:
0:01:25:51.208 cpu6:1048)LVM: 4476: vml.02000d0000600a0b80000f229e000002554777b7
92313734322d39:1 may be snapshot: disabling access. See resignaturing section i
0:01:25:57.042 cpu6:1048)LVM: 4476: vml.02000d0000600a0b80000f229e000002554777b7
92313734322d39:1 may be snapshot: disabling access. See resignaturing section i
0:01:26:01.267 cpu3:1048)LVM: 4476: vml.02000d0000600a0b80000f229e000002554777b7
92313734322d39:1 may be snapshot: disabling access. See resignaturing section i
0:01:26:38.585 cpu4:1049)LVM: 4476: vml.02000d0000600a0b80000f229e000002554777b7
92313734322d39:1 may be snapshot: disabling access. See resignaturing section i

Warning: This solution might not be a 100% safe solution so it's recommended to use your SAN admin  tools to take a snapshot or lun copy before doing these steps.

In most cases this situation can be resolved by doing the following steps:
  1. Choose the ESX Server in viclilent and Click on Configuration / Advanced Settings.
  2. Click on LVM -> LVM.DissallowLVMSnapshot 0 -> LVM.EnableResignature 1
  3. Then click OK to apply settings.
  4. Click on "storage adapters" and click the "rescan" button (upper right). That should let you see the volume again.
  5. Right click the vmhba (under the controller adapter for your machine) and click "rescan".
  6. Then the volume should be visible.
  7. Then when you go to the summary tab, you right click and click "refresh" and you should see your storage1 volume (or whatever you changed it to).
  8. Choose the ESX Server in viclilent and Click on Configuration / Advanced Settings.
  9. Click on LVM -> LVM.DissallowLVMSnapshot 1 -> LVM.EnableResignature 0
  10. Click OK to apply settings.
This situation has been observed on several different ESX 3.x versions.

References:
http://www.vmware-tsx.com/download.php?asset_id=49
http://activeanswers.compaq.com/ERC/downloads/4AA1-0820ENW.pdf
http://communities.vmware.com/thread/72948
http://communities.vmware.com/thread/60710
http://communities.vmware.com/message/868316