On Wednesday 02 June 2004 15:51, Glenn English wrote:
>On Wed, 2004-06-02 at 10:59, Jon LaBadie wrote:
>> I doubt there is any tapedrive that is "too fast" for your
>> disk drives.
>
>I thought so too. But when dump is running from one disk to the
> other, it reports speeds about 20% higher (~10MB/s) than it does
> when running from disk to tape (~8MB/s). I can get dump to stream
> by specifying a 1MB blocksize and making sure there's no other disk
> activity.
>
>The problem seems to be with writing and reading at the same time.
> The disks (IDE 7200 RPM Seagate Barracudas) don't seem to be fast
> enough to do the seeks and additional IO -- the access LED is on
> continuously, and the tape is stopping, rewinding, and writing very
> frequently. Just with the VS160 -- there's never been a problem
> with the DAT drives I've used in the past.
>
>> Are you sure your configuration is using amanda's holding disk
>> feature.
>
>Absolutely. amdump creates a directory in /amandadisk, and dumps
> from the net are stored there. If there's a tape in the drive, they
> are moved to tape. Otherwise I can get them on tape later, with
> amflush.
>
>> From the holding disk, amanda uses the equivalent of dd to send
>> a complete dump from disk to tape. Only if the holding disk is
>> not being used for the dumps might the speed of tar/dump be a
>> factor.
>
>I started using the tar/dump/dd commands directly (for
> troubleshooting) only after a couple days trying to get Amanda to
> stream the tape.
>
>If I've misinterpreted or misconfigured something, I'd certainly
> like to hear about it.
I get the impression that you are backing up something thats on the
same drive as the holding disk, and that possibly dma may also be
missfireing somehow. Any current ide drive can do 30+ Mb/sec if left
alone by other tasks, often quite a ways on the + side.
If you are not using spindle numbers in your disklist, maybe it would
help to prevent thrashing of seeks all over the place because more
than one dumper is attacking the drive simultainiously.
This might mean that the tape would stop and do a bit of shoeshining
in between files, but a given file should be able to be 'poured down
the pipe' non-stop.
There is also an algorythm string in amanda.conf that adjusts the
dumporders a bit, I have mine set to to the largest dump first, so
that once its done, there is a good chance the rest of the thing is
already in the holding disk and I get the drives maximum speed once
it actually starts.
In this case, it seems he needs two disks assigned as holding disks,
with the hope that amanda would write to one, then the other,
alternating such that the one being written was not being read by a
taper at the same time.
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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by Gene Heskett are:
Copyright 2004 by Maurice Eugene Heskett, all rights reserved.
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