On Wed, Dec 21, 2005 at 11:58:05AM -0800, Keith Nicewarner wrote:
> I'm new to backups (much less Linux or AMANDA), so forgive me if I'm
> missing some basic concepts.
>
>
> .... I think I've resolved the last issue, but here's the
> annoying thing: It keeps wanting me to put in a new tape -
> even though the previous tape wasn't full or even used.
> Is this normal?
OK, basic concepts 101 on tape usage.
Amanda only overwrites tapes, it never ever ever appends
to the end of a tape it used in an earlier session. So
don't even think about running amdump today, sending the
data to a tape and then adding tomorrows run to the same tape.
Early in a dump run amanda will see if it has a valid tape
to use. When it does find one it writes some amanda metadata
to the start of the tape (aka the amanda tape header). As far
as amanda is concerned, any data that was on that tape before
this is gone, even if it doesn't write any backup data to the
tape. I.e the tape has been "overwritten", the data is gone.
Amanda can also free up the index files and logs for the earlier
dump on that tape.
Amanda expect you to label and rotate the usage of a number
of tapes. The number of tapes is your choice, but a good
rule of thumb for the minimum suggested is 1 plus twice the
number needed for taping a dumpcycle. I have a dumpcycle of
7 days, 6 runs per dumpcycle and I generally use only one tape
per run. So my minimum according to that formula is 1 + 2 * 6,
13 tapes. Remember that is a recommended minimum, I actually
rotate 24 tapes.
You inform amanda of how often it can reuse tapes with the
tapecycle parameter. If you set tapecycle to 5, then it can
not reuse the last used tape until 4 other tapes have been used.
Tapecycle does not have to match the actual number of tapes in
rotation. My tapecycle parameter is 18 though I rotate 24.
This lets me gracefully handle (i.e. no action on my part)
situations like the occasional dump that needs two tapes to
compete or the occasional failed tape.
> Since I haven't really gotten a good backup, how can I
> start fresh? It won't let me reuse the test tapes.
> How can I wipe the tapes clean and make AMANDA think
> it's the first day of operation?
>
To reuse a tape, use amrmtape then relabel it (probably -f option).
I once ran a script to refresh a config directory to starting
state. But it was a long time ago, so no guarentees. I think
it removed the logs, reports, curinfo, and indexes. In my case
I keep these in separate directories under the config root so
it was easy. Optionally I also I recreated, from previously
saved copies, tapelist, amanda.conf, changer.conf, ???
--
Jon H. LaBadie jon AT jgcomp DOT com
JG Computing
4455 Province Line Road (609) 252-0159
Princeton, NJ 08540-4322 (609) 683-7220 (fax)
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