Tape usage - CommVault Galaxy 5.9

[ITtekkie]

Can anyone tell me why - having two 400GB tapes in the library for a Full backup that is 530GB in total, that Commvault Galaxy puts 333GB on one tape (not a problem) then puts 20GB on the second tape (which was totally empty prior to this) and then sits and sulks because it can't find a third tape to continue the backup?
I could understand it if there was data on the second tape, but there wasn't and there was more than enough capacity for the backup to complete !
So why does CommVault insist on using a third tape?

 

[birky]

It shouldn't do...have you looked through the logs to find out why it can't continue on the 2nd tape if there wasn't any data on it?

PinnacleData Systems Ltd (UK)

 

[ITtekkie]

Hi Birky,
Yes, we've looked through the logs and there is nothing untowards (all the jobs completed normally).
All they tell us is that the first tape was filled and an EOM marker added, the second tape mounted (and used for the 20GB) then message upon message about the backup could not continue as there was insufficient media in the scratch-pool (despite there still being 300GB spare on the media that was mounted !)
We have now raised a ticket with CommVault about this, I'll post the response as and when we receive it.
Regards
Pete

 

[birky]

Very strange...if you use the Check Appendable Media script does Galaxy pick up the tape in question?

Lot to be said for using disk as your primary storage ;-)

PinnacleData Systems Ltd (UK)

 

[JG5]

Are you backing up directly to tape, or is this an AUX copy from disk to tape?

 

[ITtekkie]

It's an AUX copy from disk to tape

 

[JG5]

Do you have compression enabled on your backups? My tape copies never consume even the native capacity of my tapes, and I suspect it is because I am compressing at the Media Agent level, usually getting at least 2 to 1 compression.

 

[ITtekkie]

Yes, we have compression enabled.. Like I stated earlier in the thread, all phases of the backup would sit comfortably on one or two tapes, but for some reason a third tape is being requested

 

[JG5]

Make sure you have hardware compression enabled on the AUX copy to tape as well. Before I enabled hardware compression on my tape copy, I was getting no more than 160 gigs onto an AIT-4 tape (200 gig native). Once I enabled it I started getting into the 260 gig range and the tape has not yet been marked full. True, you should not mix compressions, but apparently Commvault handles it on a per copy basis, so using software compression on your primary disk copies does not conflict with hardware compression on your tape copies. My throughput basically doubled also. I was hitting 107 gig per hour (roughly 30 meg per second) to a single AIT-4 drive just a little while ago.