Amanda-Users

Re: Tape labelling and strategy

2002-11-29 07:41:26
Subject: Re: Tape labelling and strategy
From: Gene Heskett <gene_heskett AT iolinc DOT net>
To: marc.bigler AT day DOT com, amanda-users AT amanda DOT org
Date: Fri, 29 Nov 2002 07:04:41 -0500
On Friday 29 November 2002 04:16, marc.bigler AT day DOT com wrote:
>Hello,
>
>I would like to rotate between multiple sets of 8 tapes because my
> changer supports maximum 8 tapes. So I have defined the following
> in my amanda.conf:
>
>dumpcycle 5 days
>runspercycle 5
>tapecycle 8
>runtapes 2
>
>When one set of 8 tapes is finished I will take it offsite and
> then start up with the next set, I plan to have maybe 5 sets
> which i will constantly rotate which means overwritting stuff.
> What kind of labelling should I use for that ? I was thinking of
> something like
>
>nameXX-Y
>
>where XX is the tape number
>where Y is the set letter, for example:
>
>mysite03-B
>
>that would be tape number 4 from set B
>
>or should I simply use "nameXX" ? But then AMANDA won't keep any
> history of the other sets... What do you think ?
>
>Regards
>Marc

What you propose is equ to having a tapecycle of 40, and would be 
much simpler for amanda to administer than it would be to maintain 
5 different amanda configuration trees and remembering to do the 
configuration switches in your amanda crontab.  What you do with 
the 8 tapes you take out each time the magazine is reloaded is up 
to you, and amanda won't care as long as they are back on-site in 
time to be re-used on schedule.

If you changed the config each time the magazine was reloaded, then 
on the first run of each different config amanda is going to think 
everything is way behind and attempt to do fulls on everything 
because she is 32 days behind schedule *for the just switched in 
config*.  It makes more sense to amanda to just give her marching 
orders and let her sort out the scheduleing.  Amanda will then have 
an inventory list of everything on the tapes, all 40 of them once 
the tapecycle has been completed once.

For your own organization, I'd imagine the regex expression for the 
tape label in amanda.conf could be modified to include an extra 
character to define which magazine group this tape belonged in, and 
amanda won't care since she will, unless something mucks the 
schedule (and I've had it happen here), use them in the order they 
were labeled anyway, NOT in the individual tapes order numerically.  
That runtapes = 2 if its used by amanda, will lead to some 
interesting human scheduleing 'adjustments' though.  Will your 
system really need that once it "gets into the beat", which will 
take dumpcycle runs for the fulls, and tapecycle runs for the 
partials IIRC?

Actually that will take longer if you follow a strategy of only 
compressing that which can be compressed, by setting everything for 
compression, reading the emails from amanda and turning off the 
compression via a change in the disklist entry for those 
directories/partitions that don't compress on a level 0 backup.

Directories full of rpms and tar.gz or tar.bz2's & such don't 
compress, and may in fact expand somewhat if run through gzip a 
second time. That takes about a dumpcycle to optimise.   Some 
expansion of level 1 and 2's is unavoidable because apparently the 
minimum size for a tape record seems to be 64k.  Such 'bookkeeping 
expansions' are too small to actually count very much in terms of 
tape past the head in the real world anyway.

-- 
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz  512M
99.19% setiathome rank, not too shabby for a WV hillbilly

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