On Sat, Oct 02, 2010 at 09:05:44AM -0400, Robert Heller wrote:
> Why does Amanda do multiple level 0 backups?  I only want 1 (and only
> 1) level 0 backup (of any given disk) in the backup cycle (4 weeks / 28
> days).  The documentation for the bump* parameters is not clear (to
> me).  I want Amanda to aggressively bump dump levels.

Hmm, I thought the descriptions in the amanda.conf(5) manpage
were pretty clear.

  [snip]
> bumpsize 10 Mb  # minimum savings (threshold) to bump level 1 -> 2
> bumppercent 0   # minimum savings (threshold) to bump level 1 -> 2
> bumpdays 2      # minimum days at each level
> bumpmult 1      # threshold = bumpsize * bumpmult^(level-1)

Two changes would increase the likelyhood of bumping levels:
  change bumpsize to a smaller value (eg. 1 Mb or 500 Kb)
  change bumpdays to 1

> I don't have enough virtual tapes to do more than one level 0 backup in
> a backup cycle.  

Yeah, I see that your setup is:

> dumpcycle 4 weeks  # the number of days in the normal dump cycle
> runspercycle 28    # the number of amdump runs in dumpcycle days
> tapecycle 30 tapes # the number of tapes in rotation

And you are telling amanda it can use up to 56 tapes per cycle.

> runtapes 2 # number of tapes to be used in a single run of amdump

I hope very few dumps take more than one tape, like none :)

When the Wendell Free Library adds 2 or 3 DVDs to its filesystem,

> /dev/mapper/WendellFreeLibrary-dvdisos
>                        34G  177M   32G   1% /dvdisos

it will never backup because its size will be greater than
your tapesize * your runtapes setting.

Even if your amdumps only use 1 tape per run and you get
the aggressive bumping you seek, I think you are on the
edge of a disaster.  Suppose a DLE gets its level 0 on
day 1 and incrementals for the rest of the cycle (days 2
to 28).  On day 29 it gets its regularly scheduled
level 0 and on days 30 and 31 it gets incrementals.  But
that last incremental wipes out the first level 0 and
makes all 27 of its incrementals lose much of their value.

Jon
-- 
Jon H. LaBadie                  [email protected]
 JG Computing
 12027 Creekbend Drive          (703) 787-0884
 Reston, VA  20194              (703) 787-0922 (fax)

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