I have a ESXi (4.1) server talking with a Windows Server 2008 R2 storage server, which presents some volumes as iSCSI targets using Microsoft's iSCSI software target; ESXi uses them as its datastores. All fine and good.
Microsoft's iSCSI implementation uses VHDs to store iSCSI LUNs, and has the ability to perform snapshots on them and then present these snapshots as additional iSCSI targets; so I can take a snapshot of an iSCSI LUN and then present it to an ESXi host in order to, say, recover a previous version of a VM.
Of course, when ESXi sees this new target, it refuses to automatically mount the VMFS volume, because it detects it as a snapshot. The usual solution would be to resignature it and mount it anyway.
But this can't be done, because the snapshot is read-only; trying to resignature it just fails.
When running esxcfg-volume -l, this is what I get:
VMFS3 UUID/label: 4e7adbec-ce616bc0-2470-000e0cafe516/ds3
Can mount: No (the original volume is still online)
Can resignature: Yes
Extent name: naa.60003fff4ea387cd98a2dfd21c4f195b:1 range: 0 - 1048575 (MB)
If I remove the original datastore, I can indeed mount the read-only snapshot; but if the original datastore remains online, the snapshot can't be mounted unless resignatured, which also can't be done because it's read-only.
So, my question is: is there any way to mount a VMFS read-only snapshot while still keeping online the VMFS volume the snapshot is based on?
Best Answer
You could temporarily create a VM running ESXi, mount the "read-only" LUN on it as read-write, resignature it, eject it and mount it on the underlying host. That is if you can get the snap to be shared by Windows as RW anyway. Sound like a plan?