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Joined: Feb 22, 2012 10:35 am
Full Name: Tom Browning

Pre-freeze and post-thaw script error handling

Post by TWBrowning »

Hi all,

We have some critical database applications that are not VSS-compatible which we now plan to backup using Veeam B&R.

I've been playing with the VMware Tools freeze and thaw scripts. I can get the scripts to run fine, and successfully quiesce our database applications; however I can't seem to make the scripts fail.

What I mean is that we want to know if VMware Tools has been unable to properly quiesce the databases. In other words if the script returns a value other than 0 we want the snapshot process to fail.

Looking elsewhere I have found plenty of references to people seeing their quiesced snapshots failing, and finding that their scripts have been accidentally returning a value other than 0. In these instances there is an error in ESXi saying pretty much exactly that; that the user-provided script exited with a non zero return code, and so the snapshot failed.

However in our environment I can't get this to happen...

I've tried generating errors using the following mechanisms:

1. Arranging a genuine failure to quiesce the system (i.e. by having the database be already frozen when the freeze command is run, or call the thaw command instead of the freeze command)
2. Exit the script with 'exit /b 1' or any other number
3. Call a file that doesn't exist in the batch
4. Enter some junk syntax

Whatever I do the script is marked as having run successfully in hostd.log and the snapshot completes. In turn this will mean that Veeam doesn't throw a failure for the job, and our failed backups will go unnoticed. Obviously this could be resolved by having the batch call some other alert function, but that seems a bit round-and-about given that as far as I can tell this should work.

I was wondering if anyone else had any experience with this that they could share? Or perhaps any straight info that in fact the snapshot will only fail if there is something that actually prevents the script from running, or crashes it? If so we can adjust our expectations and react accordingly.


Tom Browning
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