On Mon, Apr 17, 2006 at 06:50:37PM +0100, Anne Wilson wrote:
> On Monday 17 April 2006 16:47, Ross Vandegrift wrote:
> > On Mon, Apr 17, 2006 at 12:15:07PM +0100, Anne Wilson wrote:
> > > The DLEs are set to a 4-day rotation, but in practice I
> > > am seeing level 0 backups almost every other day, for all of them.
> > >
> > > It would seem reasonable, to me, based on the small amount of changes,
> > > to have a level0 weekly, for all of them, I think.
> >
> > Hi Anne,
> >
> > If you want a level0 weekly why not set your dumpcycle to 7 days? This
> > basically tells Amanda to try and do weekly level0 backups and
> > incrementals are okay in between.
> >
> > Another thing you can do that helped me out a lot - change the bump
> > parameters! I work with a fairly large Amanda setup where disk space
> > is usually at a premium. I was able to save a lot of space by tuning
> > the bump parameters to do more higher-level incremental backups.
> >
> > While the system previously wasted a lot of diskspace in the second
> > half of the cycle doing level 1 and 2 backups, now it usually bumps
> > every day, hitting level 5 or 6 by the end of the week.
> >
> > Of course you take a hit on restore time, but restores are pretty
> > decent from virtual tape as it is, so I'm not too concerned about
> > there being five or six steps instead of two or three.
>
> Here's an example of what I meant about bumping things.
>
> home had a level0 on the 7th, 9th, and 10th of April, then
>
> Friday, 14th
> borg /Public 1 0 0 71.1 0:0 165.8
>
> 0:0 3740.5
> borg /home 0 23329 21026 90.1 83:1 4308.8
>
> 82:2 4352.8
> borg /home/anne/Photos 1 3 4 -- 0:0 15043.1
>
> 0:0 40255.2
>
> with no mention of bumping or promoting. Then
>
> Saturday 15th
> planner: Full dump of borg:/home/anne/Photos promoted from 2 days ahead.
> planner: Full dump of borg:/Public promoted from 2 days ahead.
> taper: tape Dailys-17 kb 1968832 fm 3 [OK]
>
> Sunday 16th
> planner: Incremental of borg:/home bumped to level 2.
> planner: Full dump of borg:/home/anne/Photos promoted from 3 days ahead.
> planner: Full dump of borg:/Public promoted from 3 days ahead.
>
> Monday 17th
> planner: Full dump of borg:/home/anne/Photos promoted from 3 days ahead.
> planner: Full dump of borg:/Public promoted from 3 days ahead.
>
> I doubt if there has been any change at all in either Photos or Public during
> that three days. I wish I could see what's going on :-(
>
> Anne
Just to be sure you understand what is happening, I'll try an
example based on your DLEs. Assumptions, 3 DLEs, photo (4GB),
public (3GB), and home (21GB); dumpcycle == runspercycle == 4.
Amanda knows from historical data that it must backup 28GB with
level 0's (4+3+21) every 4 days. It would like to balance the
daily runs with 7GB of level 0 each day plus incrementals. But
on some days there are no level 0's scheduled as you have so
few DLE and such uneven sizes. Both contribute to lots of
promotions. Amanda takes the opportunity this run to get up
to that 7GB balance by doing early level 0's of photo and public.
Of course the next day there are no level 0's scheduled. But
again amanda tries to balance.
If instead the home DLE were 3 or 4 chunks, amanda would find
a more balanced situation and there would be few(er) promotions.
One of the goals of the amanda planner is to have a consistant
sized backup each run. That is clearly not going to happen
with the DLEs you are backing up. If you want to defeat this
aspect of amanda's planning the parameters are there, probably
maxpromotedays 0 is what you want.
--
Jon H. LaBadie jon AT jgcomp DOT com
JG Computing
4455 Province Line Road (609) 252-0159
Princeton, NJ 08540-4322 (609) 683-7220 (fax)
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