On Sat, Jan 31, 2004 at 01:36:32AM +0100, Josef Wolf wrote:
> Hello!
> 
> I set up amanda with chg-disk. By design, dumps are done to holding disk and
> copied to the disk afterwards. This copy operation makes the machine pretty
> much unusable for interactive usage (puts almost everything to swap).
> 
> Now I wonder whether there is a way to omit this copy operation. First
> thought was to disable holding disk (or setting it to 0). But (AFAIK) this
> would disable amanda's ability to dump several DLEs in parallel.

If you can design a way to simultaneously write several dump streams
to a tape (remember you are emulating a tape) but have each of them
appear on the tape as separate, contiguous files, perhaps some one
could work on coding it.  But I doubt the design is possible. :(


Are you sure it is the copy operation that makes your system unusable?
I would expect disk to disk copy to be a fairly short part of the
total dump time and effort.

Is the holding disk the same physical drive as the virtual tapes?
That would be a poor choice.

Are either/both the holding disk and the virtual tape disk IDE type
drives rather than SCSI.  IDE drives do take substantial cpu cycles
compared to SCSI drives.

If you haven't tested the backup without a holding disk, perhaps you
should.  It may surprise you with a sufficiently quick total dump
time despite the lack of a holding disk.

Are you doing server side compression rather than client side?
Compression processes take lots of cpu cycles from interactive sessions.

You might consider setting a "nice" value on your backups.  It should
not seriously impact the time the dump takes, but would give preference
to interactive usage when there is cpu contention.


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