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Catalog backups to lower version Media Servers - Not Always any Error!

Level 6
Partner Accredited Certified

We all know that you shouldn't back up a client to a Media Server of a lower version of NetBackup but sometimes it is easy to make an oversight.

An example cropped up recently for me at a straight forward staged upgrade.

The plan was a Master Server upgrade in week 1, let that settle for a couple of weeks before upgrading the Media Servers then a couple more weeks and upgrade all clients - change control / rollback options and all that!

Along the way it was decided to virtualise the Master Server too.

Sounded OK until we did the testing when everything worked great apart from the Catalog backup which went to a Media Server (The Master being virtualised could not have tape drives)

The backup failed with a 154 - Storage Unit is not compatible - storage unit characteristics mismatched to request.

Couldn't find any tech notes and the penny hadn't quite dropped when I first saw the error, especially as a normal MS-Windows file system backup of the Master worked fine without error to the same Media server.

I raised a case anyway as there were no tech notes relating to this but before long worked out the version mis-match would be the issue.

During my conversations with Symantec Support it became clear this was a issue and had we gone to or less it would have actually worked without the 154 error - but it may not be a valid Catalog Backup as the new 7.5.x protocol would not have been understood by the 6.5.x Media server and so in a DR situation a Catalog recovery may not actually work!

I was told that a new protocol was added to that would force it fail in that scenario but prior to that there was no check made.

I found this quite alarming, especially as there was no tech note about it so I asked for one to be produced.

This was done last Friday evening (21st February 2014) :

However it does not cover the possibilty that anything less than a Master would happily backup to a lower (6.5.x) Media Server - but your Catalog backup may be no good!! - so I decided to write this blog to warn anyone who may have overlooked this and if nothing more for the error message to get picked up on a Google search to provide a bit more info for anyone who experinces it.

In our case it just means upgrading the one Media Server along with the Master so that there are no Catalog backup issues from day 1 - I guess that is where full testing of a plan comes in handy...

Hope this helps protect someone