On Tuesday 20 July 2004 19:51, Mike Fedyk wrote:
>Kris Vassallo wrote:
>> The disks in the venus box are all SATA 150 drives, SCSI is way
>> out of the price range for this amount of space. If venus is the
>> machine that is taking forever to do the estimates, is it possible
>> that 1. estimates start on all machines, 2. the estimates finish
>> on the smaller remote file systems first; these systems begin to
>> dump. 3. now along with the backup server trying to do an estimate
>> on its own disks, its also dealing with a dump coming in from
>> remote systems and all of this together is slowing it down? Do I
>> have any valid ideas here?
>
>On my Amanda 2.4.4p2 from Fedora Core 2, the dumps wait until all
>estimates finish before starting.
>
>Is there an option to change that?

Unforch no.  The way amanda works, amanda requires full knowledge of 
what she is supposed to do in order to work out a scenario that will 
fit the available storage space.  This only takes a couple of seconds 
once all the estimates are in and then the dumpers are launched, one 
per spindle number.

You would be better off to put in some spindle numbers so that amanda 
can know for sure that she can access each disk exclusively, 
otherwise she may launch 3 or more dumpers all attacking the same 
disk(array) which will lead to some time loss due to head thrashing 
as the heads seeek back and forth to satisfy more than one dumper.

I'd think each raid array should have its own spindle number.  I don't 
run any raids here at home, but I do give every disk that amanda 
touches its own spindle number even if its in another machine playing 
client.  Each partition on that disk has the same spindle number in 
the disklist, and it did cut my times down by at least a half an hour 
overall in an approximately 4 hour run.

Also, as has been noted here, the lack of a holding disk can slow it 
down quite a bit once the backups are actually being done because the 
drive cannot service more than one data stream at a time.  Without 
that holding disk buffer, any cpu based compression may slow it down 
enough that the drive will do some "shoe shining" as it stops for 
lack of data, rewinds a bit and then starts back up almost instantly 
as its buffer fills.  Atapi/ide disks big enough to buffer what you 
want to do aren't too much over a $100 bill these days, or often come 
with a rebate form that reduces them to that price range.

-- 
Cheers, Gene
There are 4 boxes to be used in defense of liberty. 
Soap, ballot, jury, and ammo.
Please use in that order, starting now.  -Ed Howdershelt, Author
Additions to this message made by Gene Heskett are Copyright 2004, 
Maurice E. Heskett, all rights reserved.