Moliere Christian wrote:

I have one DAT tape on one server and I'd like to use amanda server

There are many different DAT-tapes.  They are also called DDS (DAT is
actually Digital Audio Tape intended for audio; the backup tapes are
usually called DDS, Digital Data Storage - but the technology is the
same; some people claim the quality of the tapes is different.)

You have 4 different types (last time I looked), and some can use
tapes of different lengths.

Here some tapetype definitions:

define tapetype DDS60 {
    comment "DAT tape drives - 60 meter tapes"
    lbl-templ "/etc/amanda/lbl-templ/DAT.ps"
    length 1250000 kbytes
    filemark 111 kbytes
    speed 380 kbytes
}

define tapetype DDS90 {
    comment "DAT tape drives - 90 meter tapes"
    lbl-templ "/etc/amanda/lbl-templ/DAT.ps"
    length 1900000 kbytes
    filemark 111 kbytes
    speed 380 kbytes
}

define tapetype DDS120 {
    comment "DAT tape drives - 120 meter tapes"
    lbl-templ "/etc/amanda/lbl-templ/DAT.ps"
    length 3850000 kbytes
    filemark 111 kbytes
    speed 380 kbytes
}

I don't have access to other DDS drives (DDS-3 and DDS-4
with their tapes).
You can actually generate this tapetype definition yourself
using the "amtapetype" program.  (Be sure to specify a
realistic -e option, or this test takes ages!)

on it. I'd like use a rotation of 5 days. Which conf file I have to
use and what are parameters to set up ?

The "rotation of 5 days" mixes up two concepts in amanda:
you have the rotation of the tapes, and the cycle between full dumps.

Say you want a full dump every week, and run your backup every workday,
you specify:

  dumpcycle 7 days
  runspercycle 5

This assumes that you have at least 10 tapes to be safe (if you have
only 5 tapes, you overwrite the full backup of the previous cycle,
and if this fails, you have nothing left to fall back).  So we let's
assume you have 10 tapes:

  tapecycle 10

Now you can fall back on the previous full dump.
You now have to label (see amlabel) all these tapes with a different
name, e.g. DAILY-01 up to DAILY-10, according to the "labelstr" parameter.

If you have only 5 tapes, you should lower the dumpcycle too:

  dumpcycle 0   # or 1 : this forces a full dump every time
  runspercycle 1
  tapecycle 5

Or, if your tapes are not large enough to hold a full dump, or the dumps
take too long each night:

  dumpcycle 2
  runspercycle 2
  tapecycle 5

With the above parameters, amanda expects you to feed a tape during
the weekends too, If not she will try to catchup each monday, dumping a
full of everything to one tape (because it's more than 2 days ago since
the last full dump on friday).

You could also have a dumpcycle of 1 week, and make a backup only on
monday and thursday:

  dumpcycle 7 days
  runspercycle 2
  tapecycle 5

Or, make a backup every day, but only to disk, and flushing it all
to one tape on friday. Just leave out the tape for the 'only to disk'
runs and insert a tape when you believe it's time to flush it all
manually (using amflush) or automatically for the next run with this:

  autoflush true
  dumpcycle 1 week  # = 7 days
  runspercycle 5
  tapecycle 5
  reserve 100   # all of your holdingdisk for incremental backups

I'll stop here.  There are many other possibilities...

--
Paul Bijnens, Xplanation                            Tel  +32 16 397.511
Technologielaan 21 bus 2, B-3001 Leuven, BELGIUM    Fax  +32 16 397.512
http://www.xplanation.com/          email:  Paul.Bijnens AT xplanation DOT com
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