On Tuesday, January 18, 2011 12:20:09 pm Jon LaBadie did opine:
> On Mon, Jan 17, 2011 at 05:17:26PM -0500, Robert Heller wrote:
> > We are running Amanda 3.2.0 on three CentOS 5.5 systems.
> >
> > We have one large (1.5TB total) file system for data (/data), three
> > 100meg /boot file systems (one on each machine) and three ~100G root
> > (/) file systems (one on each machine).
> >
> > We are using a 2TB USB disk for backup storage, with a disk-based
> > (virtual) tape changer. The tape changer is set up to have 200GB
> > 'tapes' with a chunksize of 50GB. We are using a 7-day backup cycle
> > and are using 1 tape per run.
> >
> > Amanda does a full backup of the /data on one day of the week and then
> > does level one backups for the rest of the week. It does a level one
> > backup of the other 6 disks on the day it does the full of /data, and
> > then does full backups of the other 6 disks on the other 6 days.
> >
> > Why does Amanda make so many full backups? Is there a configuation
> > parameter we need to set to change this?
>
> Amanda tries to level out, or "balance", the amount of data sent
> to tape each day of the seven day dumpcycle. The mechanism it
> has to achieve this balance is to "bump" a DLE to a higher level
> (reducing the amt of data sent to tape) and "promoting" a DLE
> to level 0 (increasing the amt of data sent to tape). The
> balancing act works quite well in configurations with a lot of
> varied DLEs or with only a few similarly sized DLEs. It falters
> in configs, such as yours, with only a few DLEs and a couple of
> widely different sizes.
>
> Making a few assumptions for an example, your file systems at
> 1/3 full, changing that data 5%/day, no compression, ignoring
> your small /boot file systems. So you would have 500GB in /data
> + 100GB total in the 3 root file systems, 600GB total. Amanda
> will attempt to tape 90-100GB each of the 7 runs. On the day
> /data gets a level 0 (500GB) amanda bumps everything it can
> trying to get as close to that 100GB "balanced value". On the
> days /data gets a level 1 or greater, its dump contributes
> only 20 or so GB to the daily total. Level 1s of the 3 root
> file systems would only increase this by about 10GB. So
> amanda promotes what it can to get close to that 100GB/day
> taped data number. /data won't be promoted so the /'s are.
>
> As Toomas noted, you can apply constraints on amanda with
> the 'maxpromoteday' setting. Bumping (not your problem)
> can also be fine tuned with several "bump" settings.
>
> Another approach is to split the /data DLE into several
> smaller DLEs. Each of these DLEs would start at /data but
> with 'include' and 'exclude' settings would only deal with
> a portion of the file system.
>
> Jon
I noted also that he does not have a Reserved setting in effect, which will
severely restrict amanda's ability to continue with the backup, but leaving
it in the holding disk should there be a problem with the tape drive.
I normally have that set to 30%, which will allow about 2 run failures to
be contained in my holding disk, which has about 650 megabytes available.
I also have autoflush enabled, but that is a local choice.
--
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)
My little brother got this fortune:
nohup rm -fr /&
So he did...
