Hi all,
thanks for answers go to
alan_at_nabeth.cxo.dec.com
"John J. Francini" <francini_at_progress.com>
and Jim Belonis <belonis_at_dirac.phys.washington.edu>
I had asked:
>
> ((...))
> I took tape backups ((...)) using the command
> dump -0 -u -b 64 -f /dev/rmt0h /filesystem
>
> I then wanted to check them (write-protection set !) doing
> restore -t -f /dev/rmt0h
> and got this output (example, date/time deleted):
> Dump date: ....
> Dumped from: ....
> Level 0 dump of /u3 on alpha:/dev/rz14a
> Label: No label
> Cannot find file removal list
>
> This happened reading the tapes on two different machines
> (3.2C and 4.0B). I am looking for answers:
> 1) What label is the 'restore' searching for ?
> 2) What is the correct command to check 'dump' tapes for
> redability and contents ?
> 3) Is there any reason to prefer 'dump' over 'cpio' and 'tar'
> for backup ? (All file systems are UFS.)
> 4) Having heard from other sources that GNU 'tar' is the only tool
> that supports true proof-reading (comparing file contents)
> directly from tape, I consider switching to that tool.
> Any experiences / warnings, especially regarding a possible
> restore using the installation CD only ?
My basic fault was to omit a filename parameter in the 'restore'
command. It worked as soon as I tried
restore -f /dev/rmt0h -t .
The effect is still funny because the 'restore' seems to stop
after reading the table of contents, so the tape is in the
middle of the 'dump' archive. So on the tape containig four
archives ('/dev/nrmt0h'), each 'restore -t' had to be followed
by a 'mt fsf' to position for the next archive.
(This implies that a correct output of 'restore -t' does not
mean anything with regard to the contents part ...)
Alan warned that 'tar' and 'cpio' might not handle device nodes
properly and that GNU tar would not be on the Tru64 install CD.
John recommended 'vdump'/'vrestore' because they include error
checking/correcting codes and can also handle AdvFS.
Jim told me that the "Label" message refers to an optional
'-L' parameter of 'dump' (which I had not given).
Regarding 'tar' and 'cpio', he sent me this URL
http://www.phys.washington.edu/~belonis/backup-torture.ps
(Zwicky's paper from LISA V on "Torture testing backup and archive
programs: Things you ought to know but probably would rather not". )
which I downloaded, but did not yet read.
When proofreading, I encountered a tape that would show correct
contents on one machine and give "read error"s on the other.
While I understand this may be an adjustment problem, it still
makes me long for a program that can verify the file contents
as well as the list of names.
So my intention is to experiment with GNU 'tar' and check
whether Tru64 'tar' can read those tapes. Even though this may
be the wrong approach for '/dev', it would still give much more
rest of mind for all user file systems.
Regards, Joerg Bruehe
--
Joerg Bruehe, SQL Datenbanksysteme GmbH, Berlin, Germany
(speaking only for himself)
mailto: joerg_at_sql.de
Received on Tue Oct 12 1999 - 10:14:02 NZDT