Hi,

* Jon LaBadie <j...@jgcomp.com> [20180409 17:34]:
> On Mon, Apr 09, 2018 at 01:20:05PM -0400, Jean-Francois Malouin wrote:
> > Hi,
> > 
> > It's with some shame that I must admit that through the long years of using
> > amanda I've never really played with the bump* parameters for DLEs!
> > 
> > I'm now in a situation that might benefit from some tuning using those
> > to aggressively encourage bumping the gnutar incremental levels.  The
> > drawback of potentially needing more tapes for recovery is not really a
> > constraint for me.
> > 
> > I have a DLE (~5TB) for which the estimates are done on the server --
> > the client, a NAS/filer, doesn't support anything else, so the DLE usage
> > info is really just from the historical usage not the current one. Any
> > ideas/hints on how should I proceed from what is currently (default
> > values I guess) configured?
> > 
> > bumppercent         20
> > bumpsize            20480K
> > bumpdays            1
> > bumpmult            4.00000
> > 
> > Would setting bumpdays to higher values (2 or 3 days) pull in the
> > direction I want to go?
> > 
> > Since bumppercent != 0, bumpsize is ignored from the man page, so I
> > guess the only important parameter left is bumppercent. Should I
> > increase it or decrease it?  I'm having a hard time understanding what
> > the doc says for amanda.conf says...
> 
> As you note, your bumpsize is ignored.
> 
> The bumpdays parameter gives the minimum number
> of dumps at each level that must be done before
> the next higher level is even considered.
> 
> bumpdays is often recommended to be set to > 1.
> The rationale being that if you have two level 1
> dumps, one could be lost without much concern.
> But if you only have a single level 1, losing it
> could be a big problem.
> 
> I question your multiplier in "bumpmult  4.0".
> It says to go from level 1 to level 2 the level 2
> needs to be 20% smaller than the level 1.  But
> to go to level 3, the size of the expected level 3
> dump must be 80% (4.0 x 20%) smaller than the
> expected size of a level 2.  And it will be really
> hard to get to level 4 as it must be 320% smaller
> than the expected level 3 (4.0 x 80%).
> 
> I'd suggest picking a bumpdays with which you are
> comfortable, get that multiplier down (1.0? 1.2?),
> comment out bumpsize, then see if 20% gives you
> what you want, if not start adjusting it.
> 
> BTW, if you make a specific dumptype for that
> DLE, you can play with the bump settings in that
> one dumptype definition without affecting other
> DLEs.  They would be using the global values.

Thank you for the explanations.
I will start experimenting with:

bumppercent 20
bumpdays 2
bumpmult 1.2

and what it leads to.

Kind regards,
jf

> 
> Jon
> -- 
> Jon H. LaBadie                 j...@jgcomp.com
>  11226 South Shore Rd.          (703) 787-0688 (H)
>  Reston, VA  20190              (703) 935-6720 (C)

Reply via email to