On Saturday 14 September 2002 12:57, Jason Greenberg wrote:
>You'll have to excuse my newbieness for this one, if you would...
>
>If I have a dumpcycle of 7 days, with 7 runs per cylce, I
> understand that I will have a full backup every 7 days. So, if
> that's the case, here are my questions:
>
>1) How many tapes are used for these 7 runs? 7? or just 1?
At least one per run, more if you permit, and amanda needs to use.
>2) does the tape change after every dumpcycle or every run?
Run, but not until the next dump, or amcheck run which is why you
have a cron job in the middle of the day that does this amcheck,
and if it fails to find the next required tape, sends you an email
advising you of this problem so you can fix it before the real run
while you are busy checking your eyelids for leaks, :-D
>3) I have 15 tapes, and I would like to use 1 tape per week, with
> 15 weeks of total history. What would the dumpcycle /
> runspercycle config be?
But to satisfy the requirements you lay out while maintaining a full
each week, dumpcycle would be 7 days or 1 week, and runspercycle
wopuld be 7, tapecycle would be runspercycle*weeks, or a minimum
of 105 tapes for a runspercycle of 7. IMO thats overkill of the
type only needed in banking or insurance, but if thats the case,
then I'd expect the cost of the tapes can be justified easily.
Please understand that amanda doesn't do two things for pure
dependability reasons.
One, because of the possibility of someone miss-positioning a tape,
amanda does not ever do an append to an existing backup on a tape
even if there is only 2 megs on a 50 gig tape. That tape is not
allowed to be re-used until its turn in the tapecycle comes around
again.
And two, again for the same reason, amanda cannot span more than one
tape with a given filesystem entry in the disklist. If a partition
at level 0 is bigger than a tape, then you must use tar, not dump,
and specify individual subdirs in that partition that are small
enough to fit on one tape in the disklist.
I do that with /usr since /usr is about 33 gigs if full, and I'm
using just one 4 gig DDS2 tape per nightly run. I have presently
37 entries in the disklist, and amanda schedules one or more fulls
every night, and then does incrementals to fill up the remainder,
attempting to arrive at a value on tape that is pretty close to the
running average tape usage. Here, that running average is about 2
gigs on a 4gig tape to cover a 46 gig drive with a full every week.
And tapecycle is 20 tapes, so I have at least 2 fulls on hand at
any one time.
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
99.15% setiathome rank, not too shabby for a WV hillbilly
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