thanks everyone.
--------Original Question-----------------
> > I was wondering if there was a way to find out a couple of things about
> > vdump(ing) a fileset off of an XP1000 v5.1a onto a TLZ10 (DDS3). Is there
> > any way to verify a dump? It would not matter if verification took as long
> > as the dump itself. Is there a way to get the compression ratio from using
> > /dev/tape/tape0_d1 vs vdump -C? Do people have any preferences for one
> > or the other?
from the anonymous SysAdmin_at_astro
The suggestion that I either do a full restore and compare the dumped
files to the originals, or do a couple of spot checks.
This is an option that I had considered. It would involved doing a vdump
-v and then choosing a random file from each subdivision of the list. This
way I can gaurante that at least one file from each of the first, middle,
and last (or whatever subdivision I choose) can be restored correctly.
If I want to do a full check, but don't have the disk space it was
suggested that I do it in several passes.
He also informed me that the drive uses Lempel-Ziv compression.
from Joerg Bruehe
> I prefer "cpio" or "tar" format for most applications,
>1) they mix header and content information, so "list the contents"
> will implicitly check the tape for readability,
>2) they support partial restore and restore into different,
> non-empty file systems, and
>3) using suitable options, they allow to read the tape on a machine
> having a different architecture.
>GNU "tar" does have a "verify" operation including a data comparison,
The gnu tar does have a verify option, but it does not work on all tapes,
dds3 being one of them.
He also brought up afio, which is, according to the website:
Afio makes cpio-format archives. It deals somewhat gracefully with input
data corruption, supports multi-volume archives during interactive
operation, and can make compressed archives that are much safer than
compressed tar or cpio archives. Afio is best used as an `archive engine'
in a backup script.
Ian worte
This is how I verify dumps (somewhat simplified):
/usr/sbin/mknod /tmp/CheckSum p
sum /tmp/CheckSum > /tmp/sums.in 2>&1 &
/sbin/vdump -f - ... | tee /tmp/CheckSum | dd bs=32k of=/dev/tape/...
rm /tmp/CheckSum
mt rewind
dd bs=32k if=/dev/tape/... | sum > /tmp/sums.out 2>&1
diff /tmp/sums.in /tmp/sums.out
alan_at_nabeth suggested:
dd if=/dev/nrmt0h of=/dev/null bs=60k
this at least gaurantess that the tape can be read through, without
gauranteeing the existance of data integrity.
Received on Wed Mar 13 2002 - 15:20:30 NZDT