We have a need to backup both VMs (at the hypervisor level), and a large NAS used for file storage. We are a charity, and have 6 sockets to manage, and so the options that seem to have both VM and bare metal backups are out of our desired budget. (I know, this is the area to make an exception if you have to, but...trying to see what I can do without.)
I've seen/tested a couple of solid-seeming backup solutions in our budget that do exactly what we need at the VM level. However, they won't do the NAS by default. The option we've been given is to present the NAS as RDM disks to VMWare. I've tried this, and I can add the disks fine. However, when it goes to actually do the backups, things fall apart.
When any of the VM-based systems are doing a backup, they're creating a temporary snapshot. However, the hosts that the VMs are running on don't have anywhere near the space that the NAS does. (This is why we have the setup we do - fast RAIDed local drives for the VMs themselves and main file storage, and then the external NAS with slower, large drives for large media files and such.) So when it tries to take the snapshot, the host datastore gets filled, and then everything on the host gets suspended due to lack of space.
Am I missing an option here (other than paying way more for an agent-based solution as well)? For example, is there some way to make the snapshots for those NAS drives happen on the NAS, while everything for the main OS happens on the main host? I'd never heard of an RDM before this whole thing came up, so I'm still not 100% sure I have my brain wrapped around all of the possibilities.
Edited to add: I'll investigate options within the NAS to do backups with its own built-in capabilities as a fall-back plan - however, I'd love to have all the backups done through the same system if possible, and we need VM backups, so still hoping there's a way to make the disks work in terms of where/how the snapshots are stored during backup.
Looks like I could possibly make the iSCSI lun a datastore, and create regular virtual disks on it, rather than having individual RDMs. There seems to be some differing info (possibly due to a config/settings change at some point?) as to whether this would do what I need, which is for the the snapshots to be saved on the NAS with the disks rather than on the local host datastore. Investigating further, but curious if anyone has tried this or has anything definitive...