Subject: Re: High interrupt CPU usage with amanda backup on a SPARCclassic
To: Francis Devereux <>
From: Hauke Fath <hauke@Espresso.Rhein-Neckar.DE>
List: port-sparc
Date: 02/10/2003 09:03:55
At 20:57 Uhr +0000 8.2.2003, Francis Devereux wrote:
>> What is the nominal throughput of that DDS-3 streamer?
>It used to do about 1 megabyte per second when it was hooked up to a faster


>It does about half that on the SPARCclassic.
>> Do you run it with HW compression enabled or not (you should not)?
>I think that I was using HW compression, I'll try turning it off.

HW compression increases the data throughput needed for keeping the tape
streaming, and it makes Amanda's job of balancing backups harder.

>> >When the amanda is backing up over the network the CPU usage is very high
>> >(see top output below), mainly interrupt and system,
>> Did you set up Amanda with client-side or server-side compression?
>> >and the tape keeps stopping and starting. Is this normal, or is there any
>> >way I can make the backup go faster?
>> Do you use a holding disk in your setup (you should)? What size?
>No, but I have a spare 1GB disk I will try.  Unfortunately some of the
>filesystems I'm backing up are much bigger than that.

The holding disk is one of the main points in Amanda and critical to its
performance. If you cannot provide a holding disk partition that is larger
than the largest partition to back up, you should at least disable
compression for the partitions that are larger than the holding disk.


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