For years I have the different Window's servers backing up to iscsi targets (via wbadmin). The Iscsi initiator on the Window VM has its own backup drive on the iscsi target (its main drives are all on DAS on the esxi host). It has worked great (and its free). The biggest pain in the ###### is in the rare even of a BMR recovery. You have to use the Iscsi initiator another windows machine to connect the the dead VM's target, share out the drive, create a new VM machine, do the restore, etc. It works but its not simple. Also, the Windows VM target machines seem forgiving if the host that runs the iscsi target is rebooted. They record a few errors about a missing iscsi target and then chug right along as soon as the iscsi target comes up.
It seems like it would be easier to just have esxi have an iscsi or NFS datastore that esxi connects to, then create the different drives on the iscsi datastore. This would eliminate teh need to create iscsi connectors inside each Windows VM and would allow for a much simpler BMR. I've done it with NFS but have never done it with iscsi. What I don't like about NFS is, if the esxi host loses connection with the NFS server, it will not reconnect on its own (I've never tried NFS4).
Obviously backup of the entire VM would be simpler for BMR. Set that aside for a bit.
Will an esxi 6.0 conntion to an iscsi targe, reconnect on its own in teh even of a iscsi target loss?
Is NFS4 any better about an automatic recconection to iscsi target loss?
Is it better to have esxi connect to iscsi or the window client?