2008/9/25 Joshua Baker-LePain <jlb17 AT duke DOT edu>:
> On Wed, 24 Sep 2008 at 6:10pm, Jamie Penman-Smithson wrote
>> I'm trying to understand why amanda (v2.6.0p2, on RHEL4) is taking so
>> long to backup just 60 Gb, the actual taping appears to only take a
>> fraction of the time. I've double checked that compression is not
>> enabled and in the report (see below) the estimation takes a grand total
>> of 0 minutes. Actually writing the data to tape only took 35 minutes,
>> the dump time was over 4 hours, over 11 hours without using a holding
>> disk (holdingdisk never).
>>
>> The tape server and client are one and the same, it's backing up a local
>> filesystem.
>
> What kind of hardware are we talking about here?  How exactly are your disks
> set up?  Where is the holding disk in relation to the filesystem being
> backed up?  What does the data look like (i.e., are there a few big files,
> or *lots* of small files)?  What type of tape drive?

The holding disk is on a local [lowly] IDE drive. The data being
backed up is on the whole comprised relatively large (couple of gig)
files stored on SAN over fibre. At first I thought that the adverse
performance was due to the IDE disk, however after disabling the
holding disk it actually takes 4 hours longer to complete. I've
considered using memory (/dev/shm) as a holding disk, however this is
only 500 MB and I'm not sure if having such a small holding disk would
make any difference.

The tape drive is part of an IBM TotalStorage 3582 tape library.

While at the moment I'm only attempting a backup of 60 GB, eventually
it'll be backing up around 2 TB.

Thanks,

-- 
-Jamie L. Penman-Smithson <jpenman.smithson AT gmail DOT com>