On Monday 29 December 2003 13:47, Andrew Hall wrote:
>OK..:). Please forgive if I have used incorrect terminology, so I
> ask again for my own clarification. Will amanda ever be able to
> write to the same tape a few days in a row, without having to spool
> to a holding disk?
>
>Say I have an AIT-2 50/100G tape, yet I only am using 20G of data.
> I could fit a full, plus a weeks worth of inc's on a single tape.
>
>If this is your design decision, mind if I ask why? Are there
> dangers in this type of theory? Just curious.
>
>Thanks again!
>
>Drew
In that event, and this is commonly done, do not insert a tape till
Monday evening, or some other arbitrary day of the week, and
configure the holding disk with enough usable space that it can hold
a weeks worth of runs. The keyword to set and define is "reserved"
in the holding disk group. Put the keyword string "autoflush yes" in
your amanda.conf also.
Then when it finds a tape on monday night, it will first flush the
acumulated backups and then proceed with the new one. Please note
though, that you stand to lose a whole weeks backups if the system
gets a tunmmy ache.
The design decision is because amanda has absolutely no guarantee that
someone will not eject the tape, or otherwise mess with the tapes
position, from one days run to the next. So amanda is designed to do
2 things:
1: rewind the tape and read the label to make sure its the right tape
in the sequence to use next, doing this with each days invocation.
This in itself destroys the location you get from an 'mt -f device
tell' between last nights run and tonights.
2. Because not all tape drives can reliably do an 'mt -f device seof'
to restore that location, and it would be a total loss to write over
last nights backup with tonights, the chance of doing that is never
taken. Hence, amanda will never attempt to append to a tape. It
*must* know that it has the tapes undivided attention during the
duration of a run. To that end, if the drive has a door lock command
or ioctl, it is used to prevent you from ejecting the tape in
mid-run.
Its inconvienient for some, but infinitly safer for all this way.
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
99.22% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
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