Server Snapshots for maintenance

[penfold]

I have been looking at Owncloud last week and almost got it up and running except that when I sync from client to server it kills the server and apparently this is due to the version we are using. I can't update it as it is the latest stable version so I want to try an earlier version instead. I've been using snapshots on a Windows 7 machine to help test new software installs and then reverting back to a nice clean state when finished. It occured to me that if I had taken a snapshot of the server before installing Owncloud I could have reverted back to before the installation rather than having to uninstall it.

 

I have read that it is not a good idea to snapshot live servers as it affects the replica's but as I would only use a snapshot to test upgrades etc, does anyone use them before making updates to servers? Or would you just fail back to the replica if you found that any upgrades/new software caused problems?

[sparkeh]

What VM software are you running?

 

I can only talk from Hyper-V experience but the snapshot problem is if you have more than one DC and USNs getting out of sync. Therefore snapshotting a DC that doesn't have to replicate is ok (imo).

However is has been addressed in Server 2012.

 

Therefore I probably wouldn't snapshot anything below 2012 in a multiple DC environment using Hyper-V.

Edited April 8, 2013 by sparkeh

[penfold]

@sparkeh we are using VMWare. My understanding is that if you have a snapshot open it can generate large amounts of data and replica's may become a problem. I was just wondering if I could use them to perform software installs/upgrades on servers to try and limit anything breaking. I suppose if replicas are working ok, you can always revert to the last working replica and it will give you limited downtime.

 

I was just wondering what would be the best practice if you wanted to test new software running in a live situation but didn't necessarily want to commit to it. I suppose reverting to a snapshot would produce the same result as rolling over to a replica in terms of data lost but having a clean state.

 

For new installs my idea was -

Take snapshot

Install software

Test

Commit if works ok

Revert to snapshot if it breaks something.

 

I suppose you could just

Install software

Test

Leave if works OK

Rollback to replica if it breaks something. (which is what we do)

 

I was just thinking what would be the cleanest way of doing it.

Edited April 8, 2013 by penfold

[kenrick]

Creating snapshots is something you have to be vary careful with. If you snapshot any server with a SQL back end you could quite easily corrupt the database. Best practice is to power down the machine before taking the snapshot and make sure you have up to date backups.

 

Paul

[teejay]

Depends what roles are on the server, if it has Microsoft SQL or Exchange then snapshotting is not supported by Microsoft, even if snapshotted from a powered off state. In these instances you would need to use your backup software. For Domain Controllers, anything before Server 2012 cannot be snapshotted, 2012 can be snapshotted if you are using VSphere 5.0 update 2 or VSphere 5.1 although this is new technology for Microsoft so I wouldn't do it yet on a live DC.

I always create a test VM to play around with new software, I don't touch production servers for testing new software and for something like Owncloud that would want to be on its own VM anyway. I tend to work on a replica when testing rather than snapshotting.

[penfold]

Depends what roles are on the server, if it has Microsoft SQL or Exchange then snapshotting is not supported by Microsoft, even if snapshotted from a powered off state. In these instances you would need to use your backup software. For Domain Controllers, anything before Server 2012 cannot be snapshotted, 2012 can be snapshotted if you are using VSphere 5.0 update 2 or VSphere 5.1 although this is new technology for Microsoft so I wouldn't do it yet on a live DC.

I always create a test VM to play around with new software, I don't touch production servers for testing new software and for something like Owncloud that would want to be on its own VM anyway. I tend to work on a replica when testing rather than snapshotting.

 

Presumably then it is not a good idea to use replica's for these servers either? It would be a better idea to backup these instead?

 

As far as I can see if I use a replica for testing then this needs to be done solely on the server, so if I wanted to test something like owncloud with clients I wouldn't be able to do this?

 

As a bit of a tangent, I've just restored a test VM from our backup but when the backup job has run again it fails with the error "the VM is no longer processed by this job". Does this mean I have configured the backup job incorrectly in the first place?