* Chris Marble <[EMAIL PROTECTED]> (Sat, Feb 17, 2001 at 07:59:17PM -0800)
> Gerhard den Hollander wrote:
>>
>> I noticed when looking through the logs that the *dumper* performance is
>> around the 1Kps (or less) on my system ,
>> whereas the *taper* gets a performance of about 7 Kps.
>> So apparently it's not the speedn of my tapedrive that's the bottleneck,
>> but soemthing within amanda.
>> I have now turned compression off and im hoping this will imporve matters.
>> Are there any other ways to tweak amanda.conf to improve dumper performance
> Best of luck finding your current bottleneck.
I did some experiments
(I still need to write this out and stick it on a proper website or
somesuch :) )
Anyway, the bottleneck is (In my case) the mutli pipe that amanda does
tar cvf - +---> holdingdisk
|
+---> | tar tvf - --> index daemon
Sticking gzip in there makes things even worse.
What I did is:
- Make sure I have a big holding disk
- Patch/Hack sendsize to use the calcsize executable iso gnutar to
calculate estimates (estimate generation went down frm well over 4 hours
to 45 minutes)
- set maxdumps to 4 (having 4 dumps in paralel to holding disk)
- dump everything from holding disk to tape.
With this I get upto 11K performance to tape
And while the avergae performance of a backup to dumper has dropped to ~
2.5 Ks (was 3K whitout compression, 1K with) I have 4 of them inparalel
giving approx 10Ks
> I never got the bandwidth setting corect on my setup so I have a LOT of
> different dump-types with different maxdumps and dumpcycle settings.
> I've got 36Gb of holding disk and a single 50Gb AIT-2 drive. One of the
> 18 machines I'm backing up has a 36Gb drive with 30Gb of already gzipped
> data on it. I work to keep the full backups of that drive confined to
> weekends.
Or use guntar, and split the big disk in smaller gnutarrable slices.
That's what I did with the 420G disk, I've made a bunch of slices all of
which are < 50G and I have 50+ G of holding disk space (on that same disk).
> My backup host is a Dell Precision 610 with 2 SCSI cards. I'm going to
> move the tape drive to the internal controlled since my holding disks are
> one the external one. Maybe I'll pick up some speed there.
> The holding disk is 4 9Gb drives striped with software RAID. I formatted
> for large block sizes and few inodes to improve large file performance.
> I'm running RedHat Linux 6.2 with kernel 2.2.16-8. Machine's got a single
> 500MHz Xeon CPU and 256Mb RAM. I know a faster CPU will help during the
> gzip phase. Will more RAM?
Depends on what else you are running.
I noticed that a 500Mhz can give rather excellent theoughput with gzip -fast.
Since it's a linux box , you may want to look into using reiserFS.
I found that file access with Reiser is faster than ext2 (although nothing
shocking) esp. when going through a lot of smaller files in one swoop.
Gerhard, <@jasongeo.com> == The Acoustic Motorbiker ==
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