-Jeff

To: <amanda-users AT amanda DOT org>
Sent: Wednesday, September 27, 2006 11:11 AM
Subject: Re: backup/amflush oddity

On Wednesday 27 September 2006 09:06, Jeff Portwine wrote:

Hi everybody,

Hoping somebody can clarify something about amanda for me.

I have my backups set to run on a 3 day dump cycle with 6 tapes, running
every evening except sunday night.    It seems to work fine, we change
the tape each morning so over the course of a week (if I understand how
amanda works right) we get two sets of full backups.    Sometimes we
forget to change a tape, and most Saturdays we don't have anybody here
to change the tape so on those days I thought that Amanda just backed up
to the holding disk and then the next morning we could just change the
tape, do an amflush, then change the tape again so that it would be
ready for the next night.

However, I've noticed that every time Amanda doesn't find a writeable
tape (usually due to the tape not being changed that day) there is very
little data written to the holding disk and the amflush is very very
small.   The day after this, the dump is much larger than usual
compensating for this.    When we change the tapes every day,  each tape
is usually around 50% full.    On a day when we forget to change the
tape or are unable to change the tape the amflush results in about 0.5%
tape useage, and the day following the day we did the amflush tape
useage is usually 85-90%.      Is this how it's supposed to behave?
How can I fix it to do a normal dump to the holding disk on days when
either we can't change the tape or we forget to change the tape?

Thanks for any explanation and/or tips.

-Jeff

Look up the keyword "reserved" as its used in amanda.conf, the default if
not specified there is 100%.  And the holding disk must, for this to work
correctly, be larger than the tape.  I believe some combination of the
above is silently effecting your backups.  I try to hold about 150% of a
tapes size for holding space, with a reserve of 30% IIRC.

--
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)
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.