On Wed, Apr 04, 2007 at 09:49:15PM +0200, Sebastian Henrich wrote:
> At 17:39 04.04.2007, Jon LaBadie wrote:
> >...
> >>
> >> I diabled the hardware compression before I used the tapes for 
> >the first time like it's described in the docs. mt shows me that 
> >hardware compression is off after inserting a tape. So I think that 
> >it's really disabled.
> >>
> >
> >The switch may not occur unless the drive actually attempts to read the 
> >tape.
> >Amanda does an initial read before any attempt to write to a tape to 
> >check if it
> >is actually an amanda tape and is the expected amanda tape.
> 
> I'll take a look at this later.
> 
> >> > Amanda also tracks the amount of compression on a per dle 
> >basis, so if you
> >> > know beforehand the ratio, you can put it in the dumptype spec 
> >section to
> >> > give amanda a head start on a good guess.
> >>
> >> How can I put the ratio in the dumptype spec?
> >
> >Can't.  The history of last 3 dumps at full and incremental levels is 
> >recorded
> >in the curinfo file for the DLE after a dump.  I wonder (don't know) 
> >if you could
> >clear or edit that file or the relevant lines.
> >
> >  $ grep comp <curinfo_dir>/<host>/_<DLE>/info
> >  full-comp: 0.386351 0.386012 0.385504
> >  incr-comp: 0.196589 0.207102 0.197036
> >  $
> >
> >The DLE I ran this sample on shrink to about 38% and 20% of the original 
> >size
> >for full and incremental dumps respectively.
> 
> My curinfo files look like this:
> 
> :full-comp: 1.403959 1.404711 1.404836
> :incr-comp: 1.953383 1.707214 1.944336
> :full-comp: 0.998471 0.998600 0.999358
> :incr-comp: 0.658643 0.633644 0.635077
> info:full-comp: 1.470862 1.470858 1.470862
> info:incr-comp: 1.920387 1.905384 1.905772
> info:full-comp: 1.048603 1.048608 1.048625
> info:incr-comp: 0.225497 0.260856 0.228623
> info:full-comp: 1.587112 1.587132 1.587116
> info:incr-comp: 0.025000 0.691057 0.681301
> info:full-comp: 1.264800 1.264797 1.264808
> info:incr-comp:
> 
> I have a problem with interpreting these values because they're 
> bigger than 1. For example in the first lines. Does this mean that my 
> backup shrinked by 140 %? Or does it grow by the factor of 1.4?
> 

A guess only ...

As I recall, your recent amdumps have encountered problems, probably
for more than the last 3 recorded values.  In such cases, the amount
of data dumped would be very small.  Yet if amanda tries to save it
to tape, it must write a 32KB block.  In that case expansion may seem
to have occured and been recorded.

-- 
Jon H. LaBadie                  jon AT jgcomp DOT com
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