On Wednesday 07 January 2004 07:28, Dean Pullen wrote:
>Hi again.
>
>I've been using amdump manually to test Amanda, and am backing up a
> full disk's file system (/dev/sda). The first time its run it
> produces a report with several gigabytes worth of backup:
>
>USAGE BY TAPE:
> Label Time Size % Nb
> VFDailySet01 0:08 3393.4 4.1 1
>
>Repeating runs on the same tape after this backup, seems to produce
> very tiny backups:
>
>USAGE BY TAPE:
> Label Time Size % Nb
> VFDailySet01 0:00 0.2 0.0 1
>
>Does amanda only save 'changes' to files, or is something incorrect
>happening here?
>
>Dean
You cannot rerun on the same tape *until* that tape comes back around
in the tapelist. And if you force it, the previous backup on that
tape WILL be lost.
Amanda, by design, cannot append to a previous runs tape. It must
have total control over the tape for the duration of each run, which
is why you must use a non-rewinding device with it.
It can use more than one tape per session, but cannot span one
disklist entries data over more than one tape. In the event an EOT
is hit, it will go on to the next tape if you have the robotics to do
so, but the failed tarfile it was writing at the time will be
restarted from the beginning on the next tape.
The length of the tapelist is a function of the "tapecycle" variable
in your /config/dir/path/amanda.conf.
Amanda keeps records of what has been backed up, and until "dumpcycle"
time has expired, won't (normally, there are exceptions that will
occur while amanda is adjusting the schedule to get in "balance") do
another full on that file, only incrementals. Amandas scheduler is
actually pretty intelligent, but doesn't often let you see it other
than an occasional overview, most of the decision makeing is done on
the fly after getting the estimates.
You need to re-read the docs and get the amanda 'way of doing things'
better fixed in your view of how a backup works. Some programs may
try and make things work by hand, but this really isn't amanda's
normal way of doing things, it is geared for one run per day only for
starters as its overall time stamps are based on a 1 run per day
situation. More than 1 run will just confuse amanda.
BRU (bring money) and Arkeia (bring LOTS more money), may be able to
do it but AIR arkeia also doesn't like more than 1 run unless the
data being backed up is all different.
This is usually done by putting the amanda invocation in the user
amanda's crontab file so its run in the early wee hours. It doesn't
need nor want any human intervention while its running. Your job is
to see to it that amanda is fed the right tape at the right time, and
having done that, to get a good nights sleep knowing amanda is on the
job.
Amanda, to run well, will need a bit more "holding disk" space than
runtapes x tapesize, if its to do a full run, but finds the wrong
tape and doesn't write it out to the tape. Thats a case where you
would read the email from amanda telling you about it the next
morning, put in the right tape and run amflush to catch it up. In
this manner, nothing is lost if the operator is off duty or forgets.
Amanda is a heck of a lady, but it takes some study to really get to
know her. :-)
--
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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