On Friday 19 December 2003 04:30, Sergei Karasiov wrote:
>I have quantum DLT 4000 scsi tape device.
>It is rewinding device.
>But amanda does not work with this device if I configure it as
>rewinding. Only if I configure my DLT as non rewinding -- amanda
> works fine.
>
>Where is my misunderstending of rewinding-nonrewinding paradigm?
>
>---
>P.S. Excuse my French.
Chuckle, french indeed!
Looks like english to me, only one miss-spelled word, even though its
an .ru return address. Do you have a french accent possibly? :-)
Welcome to the list, and I'll try to answer.
Amanda demands, and expects, that the tape will be left where its at
at the end of each write so the next file can be appended.
Imagine that if you were using the rewinding device, by definition
when the file and path to the device is closed at the end of each tar
session as defined in your disklist on a per entry line basis, what
would happen if it wrote the first tarball of say 1.3Gb, closed it,
causeing the tape to be rewound, then opened it again for writing the
next entry in your disklist. Why of course, the first file would be
over-written! And the second file would be overwritten by the third,
ad nauseum. Thats not a Good Thing(tm) :)
Therefore amanda demands a non-rewinding device. In fact, the only
time amdump re-winds the tape is when its inspecting the label to see
if its the right tape, and if it is, then the rewind will be done
again, and the label rewritten with the new current date in this
header, everything else is as read from the header its over-writing.
Its left in position at the end of that write, and the backup run
then begun.
At the end of the backup run, the tape is left at that position, and
you can do a "tell" on the device to see where its at.
For me, this is handy because I can run a script after amdump is done,
tarballing the indices and configs which includes the data for the
tape just generated, and append this to the end of the tape if there
is room for it on the tape as reported by a "tell". I've reduced the
tape capacity in my tapetype, coercing amanda into leaving enough
room on the tape for these last 2 files. The idea being that if I
have to do a bare metal recovery, I can go read and unpack the last 2
files on the tape, and have full knowledge of the complete tape
archives contents when doing the restore. This last bit is something
I'm doing, but I don't know if anyone else is.
Now, Sergei, does this help make sense out of why amanda requires the
non-rewinding device? (says me, ducking) :-)
--
Cheers, Gene
AMD K6-III@500mhz 320M
Athlon1600XP@1400mhz 512M
99.22% setiathome rank, not too shabby for a WV hillbilly
Yahoo.com attornies please note, additions to this message
by Gene Heskett are:
Copyright 2003 by Maurice Eugene Heskett, all rights reserved.
|
