Clarification on backup of .IMG files

[jdp404]

Can someone provide clarification on the best practice for backing up mounted/connected IMG files in v4.1? I apologize because I realize this has been covered, but I don't see specifics for v4.x, which appears to have changed things a bit. I see that in previous versions, backing up a mounted/connected IMG file was not supported: http://www.starwindsoftware.com/forums/ ... t1187.html
Can Windows 2003' own VSS be used on the Starwind server to backup a live/mounted IMG file? Can you simply use Windows Explorer or any file level backup utility to copy/backup the actual .IMG file directly? If not, what is the best approach to do this?

Thanks,
Jonathan

[Robert (staff)]

Jonathan,

At the moment there would be two options for online backup of the mounted image files:

1. Mirroring. You can create a Mirror (RAID-1) device by means of StarWind and actually connect two images that will be assynchronously replicated. So in other words, you will have two image files instead of one.
2. CDP&Snapshots. StarWind supports creating Snapshot&CDP device - an image file that will manually or automatically create Snapshots that you can later mount/roll back to at any time.

Both options are available in StarWind Enterprise Edition. (http://www.starwindsoftware.com/starwin ... ise-server)

Additional information can be found in the Help file of StarWind iSCSI SAN and on technical documentation section of our web page http://www.starwindsoftware.com/technical-papers

Thanks,
Rob

[min]

does starwind plan to provide a Volume Shadow Copy writer? to be installed on starwind server. (not a VSS provider that will be installed on the clients)
this will allow the image files to be backed up in the same way as any database files whose engine supports VSS.

[Constantin (staff)]

We`ll add support of creating CDP snapshots for HA devices.

[Aitor_Ibarra]

Min,

There's a published example of using Microsoft's DPM to backup starwind: http://www.starwindsoftware.com/using-starwind-with-dpm

DPM uses VSS, so I don't think a special VSS writer for Starwind is strictly necessarry to get a consistent backup - I guess the .img is treated by VSS as any other open file.

Presumably you could also use Windows Server Backup or anything else which does VSS snapshots.

However, this doc is pre 5.0 HA; I would imagine that it might be more difficult to backup an HA .img using VSS without a specialised VSS writer.

cheers,

Aitor

[Constantin (staff)]

So, may I ask what solution did you choose for backup?

[broman]

Revisiting the need to backup a running .img file with *guaranteed integrity*, it occurs to me the solution suggested by this document http://www.starwindsoftware.com/using-starwind-with-dpm is unacceptable. Even though the VSS writer on the Starwind host will kick in, the state of the client using the volume contained in the .img is unknown at the time of the .img backup. The VSS writer on the client would have to be somehow invoked first and ONLY THEN could the .img be considered committed and ready to be backed up. Am I wrong?

Min,

There's a published example of using Microsoft's DPM to backup starwind: http://www.starwindsoftware.com/using-starwind-with-dpm

DPM uses VSS, so I don't think a special VSS writer for Starwind is strictly necessarry to get a consistent backup - I guess the .img is treated by VSS as any other open file.

Presumably you could also use Windows Server Backup or anything else which does VSS snapshots.

However, this doc is pre 5.0 HA; I would imagine that it might be more difficult to backup an HA .img using VSS without a specialised VSS writer.

cheers,

Aitor

[Max (staff)]

Broman,
we are working on this functionality, expect to see an HA +1 and +2 replication configurations in the nearest future.
Meanwhile I would recommend to set up DPM on the client if you want maximize the snapshot consistency.

[Aitor_Ibarra]

Broman,

Yes, thinking about it, you are right.

Revisiting the need to backup a running .img file with *guaranteed integrity*, it occurs to me the solution suggested by this document http://www.starwindsoftware.com/using-starwind-with-dpm is unacceptable. Even though the VSS writer on the Starwind host will kick in, the state of the client using the volume contained in the .img is unknown at the time of the .img backup. The VSS writer on the client would have to be somehow invoked first and ONLY THEN could the .img be considered committed and ready to be backed up. Am I wrong?

Min,

There's a published example of using Microsoft's DPM to backup starwind: http://www.starwindsoftware.com/using-starwind-with-dpm

DPM uses VSS, so I don't think a special VSS writer for Starwind is strictly necessarry to get a consistent backup - I guess the .img is treated by VSS as any other open file.

Presumably you could also use Windows Server Backup or anything else which does VSS snapshots.

However, this doc is pre 5.0 HA; I would imagine that it might be more difficult to backup an HA .img using VSS without a specialised VSS writer.

cheers,

Aitor

The best you would get would be a "crash consistent" backup, so you would be dependent on the applications on the clients to be able to roll back uncompleted transactions. The only way to get a fully consistent backup is to either have the clients trigger it, or if virtualising, have the hosts tell the guests to get consistent. Alternatively schedule a shutdown of all the clients and then backup the Starwind server, but that might not be acceptable.

[anton (staff)]

Upcoming version (post V5.5) will have VSS compatible HA. FYI.

[dmmattix]

Just a bit of clarification on using the CDP targets with ESXi V4.1 for backup. If you connect the target to the guest OS (Windows) this will work. If you connect the target to ESXi via VMFS then it will not work. CDP needs a client VSS to perform its snapshots and VMFS does not provide one. It was suggested you could connect the CDP target via the Raw Mapping provided by VMFS but everything I have read indicates this should be used sparingly not as a standard practice. The connecting of the Snapshot and CDP target to VMFS caused my NAS server to fill up memory every time it attempted to do a snapshot as no suitable VSS client was available. The basic target (.img files) work just fine and perform very well in this (via VMFS) scenario just don't try to use CDP (.ibv files) as you will have problems.

Just trying to save someone the weeks of problems I had.

I will try the Mirrored .img files and see if that provides a solution on the NAS box. I will also try VMFS Snapshots as that also could work for a backup solution with an ESXi backup agent.

Mike

[Max (staff)]

Mike, thank you for suuming everything mentioned above.
We are constantly developing our software to make it better, it is just a matter of time to release a VMware compatible Snapshot agent for direct datastore backup.