ESXi iSCSI datastore rsync, worthless backup?

[Keith Savoie]

Not exactly a direct FreeNAS question but hoping someone can provide any insight.

I have a primary FreeNAS box set as the datastore via iSCSI of a HP ESXi head. I have another FreeNAS box configured as backup to the primary that is scheduled to rsync the directory with the datastore.

This config seems to be successfully operating however is rsyncing a datastore a worthless backup? Is the resulting backup a recoverable datastore in the case of disaster?

Thanks for any input.

 

[HoneyBadger]

rsync the directory with the datastore.

This sounds like you're using file extents for iSCSI, is this correct? ZVOLs are faster as of the new iSCSI target in 9.3 so you should be using those.

Either way, the viability of your datastore and VMDKs on it may vary without leveraging the "VMware-Snapshots" functionality in FreeNAS. Without that, your data won't be guaranteed snapshot-consistent at the VMFS level - it will be at the ZFS level but there might be missed writes or metadata that VMware could choke on.

Scheduled jobs via VMware-Snapshots menu will make the vCenter API call to snapshot all VMs on the specified datastore, and then it will snapshot the ZFS filesystem associated with it. Then you can replicate that snapshot, and you'll be guaranteed to have those snapshots be VMware-consistent since they were taken prior to the ZFS snap.

http://doc.freenas.org/9.3/freenas_storage.html#vmware-snapshot

 

[Keith Savoie]

Still running 9.2.x. as from a thread I started earlier, iSCSI config doesn't survive the upgrade/migration to 9.3.x and I haven't taken the time yet to manually migrate all my VMs, update then migrate back on.
In current config I have a independent zvol set as the repo of the datastore (mnt/vol01/iscsi). Then I have an iSCSI extent mapped within that (mnt/vol01/iscsi-data01). I was under the impression that I would not be able to take advantage of any VMwware-Snapshots functionality as you need a full ESX license. I am only using the free ESXi version.
Thanks.

 

[HoneyBadger]

Right, I remember warning you about the iSCSI target switch in the upgrade.

It's scary stuff; but having been on 9.3 for a while now, you do want to make the time to switch. Performance is significantly improved and getting access to the VAAI primitives and other functionality is a serious feather in the cap.

As far as the VMware-Snapshots, free ESXi allows for regular, manual snapshots just fine (unless that's changed recently.) What it doesn't allow is access to the vSphere Storage API - but thankfully you don't need that access to do a backup via ZFS snapshot. You just take a VM snapshot, then a ZFS snapshot, then delete the VM snapshot. VMware just figures you're indecisive, but ZFS has a crash-consistent VMDK stored safely away in a snapshot.