Unable to Take a Quiesced VMware Snapshot of a Virtual Machine? Virtual machines may become unresponsive during quiesced backup operations (VMware snapshots) on a virtual machine with Microsoft iSCSI LUNs attached within the guest operating system.
When using the VSS or SYNC driver within a virtual machine, the tools attempt to quiesce all I/O (storage, memory, etc) within the virtual machine. Because the virtual machine has a MS iSCSI initiator LUN attached within it, the VSS or SYNC is unable to quiesce the guest operating system in the time allocated for the quiesce operation.
VMware snapshot operations (quiesced or non-quiesced) do not provide backups of any network attached storage mounted within the guest operating system (including iSCSI LUNs mounted via in-guest iSCSI software initiator, or CIFS/NFS share mounted within the guest operating system). For information on creating backups for these types of guest accessible storage, refer to your backup solution provider or storage hardware vendor for an appropriate solution.