On Tue, Dec 21, 2004 at 12:49:01PM +0200, Shai Ayal wrote:
> Hi all,
>
> I'm trying to set up an backup system in our company. We have two major
> file systems to backup - one is the homedirs of everyone, including mail
> in Maildir format, and the other is data.
>
> Our idea was to have two computers -- one would hold the data and homes,
> and the other would back it up daily to a disk. Additionally, once a
> week or so we would to a tape backup to take off site.
>
> The data is quite huge and it is often updated but only in small
> amounts, i.e. we have about 80GB of data, and we add less than 300MB
> each week. ...
Huge is in the eye of the beholder :)
Some people on the list describe their environments in TB, not GB.
> ... Clearly doing a full backup every week is very wasteful.
Not necessarily. I recall an incident where I did not realize a file
critical to my system had been damaged. However it did not come into
play except during boot, and unix systems don't often reboot (at least
mine :) When I stepped through my weekly level 0's I found when it
changed, restored it, and was able to determine the cause based on
what else happened at that time.
>
> Homedirs are standard and I think the usual amanda backup algorithm will
> work with no problem.
That's a problem with standard's, there are so many of them :)
>
> Problems:
>
> 1. Can I implement two different backup strategies, and write the result
> to the same tape? i.e. although the strategy for home and data is
> different, they would go in the same tape if they are scheduled for the
> same day?
Not sure you will really have two different stratagies. The simple answer
is no, you can't have two amanda configs writing to the same tape. But
there is a great deal of flexibility in how each backup entity (called a
DiskList Entry or DLE in amanda) can be configured. Different dumpcycles,
exclude lists, dump program, priority, strategy, ...
>
> 2. What is the recommended strategy for backing up the data? "strategy
> nofull" seems appropriate, but does it work? -- the manual seems to be
> ambiguous about it. Does anyone have other recommended strategy ?
>
I'm pretty sure some of those strategies are for those admin's who want to
manually schedule full backups. Maybe there are other uses of which I'm
unaware.
But amanda does assume having full backups done.
> 3. On the same subject, can someone help me with the technical terms of
> backup level: I understand level 0 is full backup, but do level 1
> backups depend on the last level 0 backup done or on the last level 1
> backup done ?
>
There does seem to be some variation in the term incremental between different
backup management schemes. Amanda terminology calls anything other than
a full backup (aka level 0) of a DLE an incremental. The various levels are
relative to the last backup of a higher (lower numerically) backup. So if
if a DLE gets a level 0 on Sunday, then any level 1 done until the next
level 0 is all the changes relative to the level 0. If a level 2 is done,
it is the changes since the last level 1 ...
> Thanks in advance for any help
>
> Shai Ayal
>
>
>
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>
>
>>> End of included message <<<
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Jon H. LaBadie jon AT jgcomp DOT com
JG Computing
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