I read this with interest as I am having similar issues.
I am using SMVI v2 with vSphere and a FAS2020 running 7.3.2P2.
I am performing hourly "NetApp" snaps of my NFS vol which stores all my VMs, and daily "VM quiesced snaps" every evening (I read somewhere that this was a good idea).
We also have Domain Controllers and Exchange & SQL servers with iSCSI LUNs (needed by SnapManager) included in these backups.
What I experience is that every evening at least 2-3 random VMs fail during the VM snapshots (timeouts when creating the snapshot). The VMs effected always seem to be those which have iSCSI LUNs mapped within them.
What I would like to know is:
1) You state in your post that making VM snapshots of VMs which have Microsoft iSCSI initiator LUNs is not supported. Can you tell me where you read this?
(in all cases, if I create a VM quiesced snapshot of the failed machines manually using the Infrastructure Client the following day, it works absolutely fine).
2) There is no option it seems in SMVI 2 to be selective in which VMs should be snapped? Therefore, do I simply ignore these random failures or is there a way to exclude them from the backup?
SMVI seems to backup all VMs in the datastore by default, and the only work around I can see would be to create different datastores for VMs which have iSCSI initiator LUNs.
In all cases though, with SMVI 2 I find that even if snapshots of a VM fail, the backup process completes and will continue to snap the remaining ones.
I did have a similar issue to you last year with ESX 3.5 and SMVI 1 whereby VM snaps would timeout on the "deleting snapshot" part of the process - and this was due to a NFS lock timeout parameter (search for SMVI, timeout - the post exists somewhere on this forum). Since then we've upgraded to vSphere and SMVI 2 and followed the best practices for NFS vols and we've never had the problem again (we also suffered timeouts on the actual VMs during snapshots whereby they would lose connectivity and pings to the servers would fail during a snapshot process - this was also solved by following the best practice NFS tweaks).
I hope you find something here useful, and if anyone else can provide some insight into my questions it would be great.
Marc