P4500 - Cannot create/remove snapshots

[George Ene]

Issue:
vRanger is unable to take clean snapshots of VMs on iSCSI LUNs (HP P4500 SAN) as part of the backup process.
The process for Manual snapshots in vSphere Client also fails with the same error message.

Error messages:
Create snapshot: Error encountered while saving pending snapshot file “/vmfs/volumes/4b8ef9e9-9a365e50-19d4-00237da8b17c/AKiCTVM003-Snapshot308.vmsn”. Reported I/O error is Generic error
Or A general system error occurred: The specified file is not a virtual disk
Remove snapshot: Unable to access file

Result:
Partial snapshots are left behind on the disk and not registered in the snapshot database. Sometimes the snapshot disk chain is intact, sometimes not.
Also, while trying to consolidate incomplete snapshots, we are having issues with the disk cloning “timing out” or getting generic I/O issues on the HP P4500 Datastores. An attempt to copy the base disks (approx. 25GB) off to a local datastore also timed out.

Actions:
- tested creating/releasing snapshots for VMs on datastores located on the HP EVA SAN = no problems
- performed Storage vMotion on VM with the problem, moving it to a datastore on the HP EVA SAN, created/released snapshot = no problem
- vRanger backups on VMs located on the HP EVA SAN are being performed successfully
- shutdown VM with problem and can create/release snapshots correctly
- restarted Host to reset SAN connections = problems still present on VMs
# call logged with HP to check HP P4500 SANs for problems
- performed test on newly created VM (see test description below) = duplicated the problem
- performed same test on VM in Christchurch and couldn’t duplicate the problem
# call logged with vRanger support to check for any possible issues with new version of software. Some other errors have started to occur in Christchurch with vRanger backups on VMs located on the P4500 Storage down here. They may be related.

Test:
- created new VM located on Fibre Channel SAN
- created/released Snapshots = no problems
- created new LUN on HP P4500 SAN and presented to VMware Hosts
- Storage vMotioned VM to new LUN on HP P4500 SAN
- created/released Snapshots = no problems
- presented LUN to vRanger backup Server
- performed vRanger backup of VM = successful
- created/released Snapshots = error creating snapshots
- Storage vMotioned VM back to HP EVA Datastore
- created/released Snapshots = no problems

Issue seems to be confined to VMs using the iSCSI HP P4500 SAN, and trying to snapshot memory state.
Similar issue:
http://h30499.www3.hp.com/t5/HP-LeftHand-P4000/P4300-G2-Starter-SAN/m-p/4653074#M1160

[George Ene]

Has this happened to you?
Any insight is appreciated.