iSCSI backup strategy

[Shad]

I'm playing around with iSCSI at the moment using the StarWind software target (free version, which importantly doesn't support mirroring). One thing that's bothering me is working out the best way to backup data. StarWind advise the use of snapshots and CDP but they advise against making 'hot' copies of the files as they can't guarantee they won't be written to during the backup. The same applies to basic .img devices.

That said, I've been testing in my environment and have successfully made backup copies of both types of virtual disk, and restored them to working condition. I think for me it could be a workable option.

However, call me old fashioned but I like to actually manipulate my backup files if I really need to (i.e. pick up one or two files out of a backup and restore them). I don't think I can easily do that with StarWind virtual disks. What I could do as an alternative is have the initiators handle backing up the data, but that isn't ideal as the system would need to run overnight.

Does anyone have any suggestions or advice on the best way to backup iSCSI devices?

Cheers

 

[KOOLER]

Generally speaking it's a bad idea to backup "volume containers" with something having no clue about what's inside... StarWind is VSS friendly software so it will flush the caches on backup app requests but... Connected initiators cannot be "fired back" to do the same so file systems layered on top of an iSCSI volume are not going to provide any consistency points. It's not about StarWind only, all solutions are the same here. There are a couple of ways to go (everything is generic unless I'll mention it's about StarWind only):

1) Disconnect initiators from your volume and run a backup. In this case there's 100% guarantee volumes are not going to be mangled as there are no active writers. Drawback - requires client downtime.

2) Configure built-in target replication (this option is a paid one with pretty much everybody I know).

3) Backup individual VMs located on an iSCSI volume. It could be either built-in solution (StarWind has own VM backup and replication) or OS / hypervisor option. Paid for ESXi and free for Hyper-V (VM replica in Hyper-V 3.0 / Windows Server 2012).

With 2) (partially) and 3) you need to check your RTO and RPO as you may not fit into async replication interval and cannot affortd to lose any data.

I'm playing around with iSCSI at the moment using the StarWind software target (free version, which importantly doesn't support mirroring). One thing that's bothering me is working out the best way to backup data. StarWind advise the use of snapshots and CDP but they advise against making 'hot' copies of the files as they can't guarantee they won't be written to during the backup. The same applies to basic .img devices.

That said, I've been testing in my environment and have successfully made backup copies of both types of virtual disk, and restored them to working condition. I think for me it could be a workable option.

However, call me old fashioned but I like to actually manipulate my backup files if I really need to (i.e. pick up one or two files out of a backup and restore them). I don't think I can easily do that with StarWind virtual disks. What I could do as an alternative is have the initiators handle backing up the data, but that isn't ideal as the system would need to run overnight.

Does anyone have any suggestions or advice on the best way to backup iSCSI devices?

Cheers

 

[Shad]

Thanks Kooler, very useful indeed