On Wed, Jul 06, 2005 at 03:44:59PM -0700, Michael Hannon wrote:
> Greetings.  We've had some problems with the amanda backups on our one 
> Solaris system.  We're still tweaking, so I won't yet go into details, 
> but I did want to ask a question.
> 
> We're trying to backup some relatively large file systems to an SDLT 320 
> tape drive.  Currently the largest file system has about 60 GB of data, 
> but the trend is upward, of course.
> 
> My question relates to the detailed handling of the holding-disk space. 
>  We're trying now to use a holding disk of 3 GB, with a chunksize of 1 
> GB.  Does this make sense?  I.e., these are mostly local file systems, 
> so amanda is going to be shoveling data pretty quickly into the 
> holding-disk area.  There are 60 of our chunks in the large file system, 
> while our holding disk can hold only 3 of our chunks.  Is it possible 
> that amanda would put chunks into the holding disk faster than they can 
> be removed to the tape drive (and, hence, conclude that there was no 
> more holding-disk space)?


Yes, if the backup were going to the holding disk.  In this case
it would not.  It would be written directly to tape.

The part you missed was that if a dump uses the holding disk,
it is collected in its entirety before being sent to tape.

The holding disk serves three purposes:
 - allows multiple DLEs to be dumped simultaneously
 - allows better streaming of a backup to the tape
 - acts as a safety net for tape problems

A large, inexpensive, disk drive (or 3 or 4) to serve as
an amanda holding disk is a good investment.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
 JG Computing
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