--On Wednesday, May 11, 2005 00:36:04 +0100 Rodrigo Ventura <yoda AT
isr.ist.utl DOT pt> wrote:
> I'm working on setting up a automated backup system using amanda
> 2.4.4p4 on a linux slack 8.1 server. The tape system is a HP DAT 72x6
> autoloader (36/72 GB tapes)
>
> Q1: Using tapetype I got the following entry:
>
> define tapetype HP-DAT-72x6 {
> comment "HP autoloader DAT 72x6"
> # data provided by Rodrigo Ventura <yoda AT isr.ist.utl DOT pt>
> length 31255 mbytes
> filemark 527 kbytes
> speed 1580 kps
> }
>
> How can I setup amanda to be less conservative, i.e. assume it can
> record a little bit more than 31GB per tape? Is there a parameter
> where I can specify the assumed compression ratio, say, something
> between 1:1 and 1:2?
You can change the length to be whatever you think will fit on a tape.
The tapetype program write random data to the drive, which evidently
has hardware compression enabled. Attempting to compress non-compressible
data (or already-compressed data) generally makes it larger instead of
smaller, thus only 31 GB fitting on a 36 GB (native) tape. You can either
turn off hardware compression on the drive and do software compression
on selected DLEs (disklist entries), which will enable amanda to very
accurately fit dumps on the tape. or you can adjust the length to a size
that approximates how much of your data will will fit after the tape drive
compresses it. If you guess too low, you may need more tapes than otherwise
needed. guess too high and you may unexpectedly hit EOT, causing the taper
process to start over on that DLE on the next tape, also causing more tape
to be used. If your daily backups are usually smaller than a single tape,
or somewhat larger and will need another tape regardless, then it may not
matter much either way.
Feel free to adjust it anytime as you get more of a feel for your data
and tapes.
>
> Q2: I'm getting "strange" messanges in dump, mostly related with
> sockets ignored by gnutar, temporary files (mail queue) being
> manipulated, etc. It seems this is the cause of several dumps being
> promoted N days ahead... Is there a way to make amanda ignore such
> messages? I can live with backups without those files. But I can't
> live with amanda promoting dumps several days ahead, all the time
> (they never get dumped this way!).
If they are being promoted, they ARE being dumped, just the level is
being changed sooner than would otherwise occur to fit your dumpcycle.
The promotions occur either to balance out daily tape usage (doing
more tonight when there's extra room on the tape gives more flexibility
tomorrow when a level0 of a large filesystem might be scheduled). It
doesn't increase tape usage (I have runtapes set to 3 on a config that
normally uses about 3/4 of a tape to allow for autoflushes if necessary,
but amanda doesn't promote everything to try and fill 3 tapes, it just
uses the 1 it normally uses).
The 'strange' messages just let you know about things that didn't get
backed up (or possibly were backed up incompletely). There's a file
in the source somewhere that lists strings to ignore, but I wouldn't
recommend changing it unless you are sure you will never care about it.
It is letting you know what will be missing/incomplete when you go to
do a restore.
>
> In other words, what exactly makes amanda promote a dump N days ahead?
> How can I know whether the promotion message is safe to ignore or not?
You can always ignore the promotion messages, unless you want to tune
your bumpsize parameters to change when the promotions take place.
>
> Q3: I setup amanda in my server, and currently I'm running it
> everyday. However, I want to increase the dump cycle, letting amanda
> run, say, three times a week. Is it safe to change such parameters as
> dumpcycle and runspercycle in mid-cycle? Say, if I change them right
> now, will it keep on working without further operations?
Yes, although it may take a few runs to balance everything out again.
Making the dumpcycle longer or increasing runspercycle shouldn't ever
be a problem (assuming your tapecycle is long enough to handle it).
Decreasing either drastically may make it impossible to fit everything
on the tapes provided, but amanda will warn you if it is unable to meet
your schedule or if you are gong to overwrite your last full backup of
a DLE.
>
> Q4: Following the previous question, is it safe to incrementaly add
> entries to disklist?
Yes, that's the best way to do it. Adding large numbers of DLEs at once
may cause some temporary scheduling problems as amanda has to do a full
backup of each new one when its added. It will eventually sort itself
out (assuming you have enough tapes), but it is simpler to add a few at
a time (or one at a time if they are very large as a percentage of your
tapesize).
Frank
>
> Thank you,
>
> Cheers,
>
> Rodrigo Ventura
--
Frank Smith fsmith AT hoovers
DOT com
Sr. Systems Administrator Voice: 512-374-4673
Hoover's Online Fax: 512-374-4501
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