On Tue, May 31, 2005 at 12:46:32PM -0700, Cameron Matheson wrote:
> Ok, thanks everyone for the help, amanda just
> succussfully backed up my computer to the tape! now i
> have to go about to the actual configuration of how i
> want to do the whole backup system...
> ... . Basically
> i'll be backing up about 25 linux servers,
Don't even think about starting backups of all of them on the
same date. Stage introducing them to amanda over the course
of a number of days where days == your dumpcycle.
> totalling about 1TB of space.
If you are not already aware, amanda is unconventional in how
it handles daily backups. Each run, "some" of your data will
get a full backup (level 0) and other data will get incremental
backups (levels > 0). Amanda does "at least" one level 0 of
each of your data items (known as disklist entries - DLEs)
during each dumpcycle. It balances the full and incrementals
with the idea of making each day backup the same amount of data.
After you determine how frequently you want level 0's (your
dumpcycle), then determine how many times during that dumpcycle
you will run amdump and this becomes "runspercycle". Divide
your TB of data by your runspercycle and that is the approx.
amount of level 0s done each run. Add in a guesstimate for
incrementals and you approximate the amount of tape needed
each run.
> I'm planning on using tar instead of dump
> (partially because one of the servers would never fit on
> one single tape,
Good reason. Note, dump and tar can be mixed, some DLEs one,
otheres the other program.
> and also because it seems that dump is not reliable on linux?).
Not such a good reason. Will that old saw never die?
> anyway, my tape-changer has 2 drives and 30 slots.
If your amanda server, and your network, can handle the load,
you can run two amdumps at the same time. Each will have its
own amanda config and DLE list. You must make sure that no
amanda client appears in both configs. This way one config
can use one drive, the other the second drive. One config
can use slots 1 to x, the other x+1 to 30.
> How often
> should i re-use tapes or ship them off-site? Also,
> right now w/ my amanda configuration i am only able to
> use the first drive in my tape-changer. is that
> normal? any other advice for someone trying to set up
> their first network-backup system?
Once you determine how much data you will backup each run
(above calculation), then you know how many tapes you will
need each run (runtapes parameter). It is reasonable to
set it higher than actually needed, amanda only uses what
is actually needed but the extra's might be needed some days.
Now you know approximately how many tapes are needed per
dumpcycle. How many dumpcycles worth of tapes do you feel
you need to maintain. Two sets at a minimum, 3, 4, 5, ...
sets is much more reasonable. Off-site, you need one or more
sets for there, one in transportation, one in use, the most
recent set for "I deleted a file last week" type recovery, etc.
Don't ask why (instead read the list archives), but don't label
your tapes "monday, Tuesday, ... Or Set 1-1, Set 1-2, ... Just
do something like "ConfigA-001, ConfigA-002, ..."
HTH
jon
--
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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