On Thu, Jul 22, 2010 at 4:04 AM, Dominik Schips <[email protected]> wrote:
> With normal configuration the 500 GB full backup to tape took about
> 10-11 hours.
>
> With the split tape config it took about 16 hours to backup 116 GB and
> amanda ist still running to backup the other data.

When doing a split write without holding disk, Amanda must cache all
of the data it writes.  That additional write can be time-consuming!
Also, when not using holding disk, your write speed is constrained by
the speed of the process actually dumping your filesystem (probably
gnutar?), which for filesystems with a lot of small files can be very
slow.

> Any advice or solution how to debug the problem (correct) and get normal
> write performance with split tape dumps config?

* Add holding disk
* Use a newer version of Amanda
* Split in memory or use a faster disk for your split_diskbuffer

Dustin

-- 
Open Source Storage Engineer
http://www.zmanda.com

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