xfsdump problem (blocksize)

[List Account <listac@xxxxxxxxxxxxxxxx>]

Hi,

I have run into a slight problem with xfsdump - though it is more of 
general nature, I hope it not too of topic.  That is, how do I determine 
the correct block size for my tape drive  (Exabyte exb-8900 mammoth). 
Using "mt setblk 0" works (and is recommended) for tar, but not for 
xfsdump. Setting no blocksize at all does not work, either.
Anyway, since I do not really understand the impact of the blocksize 
(and on what it is dependand) I do not really dare to fool around with 
it - it is finally about backup.


Below is the output, first for no blocksize set and second for variable 
blocksize:

root@kaperfahrt:~/bin# xfsdump -o -l 0 -v trace -F -L test -M test -f 
/dev/tape /dev/hdg1
xfsdump: version 3.0 - Running single-threaded
xfsdump: WARNING: most recent level 0 dump was interrupted, but not 
resuming that dump since resume (-R) option not specified
xfsdump: level 0 dump of kaperfahrt:/mnt/d_hdg1
xfsdump: dump date: Mon Aug 13 21:22:55 2001
xfsdump: session id: e8ec9aa6-dd82-43ce-91f8-655664a5f91a
xfsdump: session label: "test"
xfsdump: ino map phase 1: skipping (no subtrees specified)
xfsdump: ino map phase 2: constructing initial dump list
xfsdump: ino map phase 3: skipping (no pruning necessary)
xfsdump: ino map phase 4: skipping (size estimated in phase 2)
xfsdump: ino map phase 5: skipping (only one dump stream)
xfsdump: ino map construction complete
xfsdump: estimated dump size: 11599985152 bytes
xfsdump: preparing drive
xfsdump: fixed block size tape drive at /dev/tape
xfsdump: unable to set block size to 1048576
xfsdump: dump size (non-dir files) : 0 bytes
xfsdump: NOTE: dump interrupted: 0 seconds elapsed: may resume later 
using -R option
root@kaperfahrt:~/bin#

syslog:

Aug 13 21:22:55 kaperfahrt kernel: st0: Block limits 1 - 245760 bytes.
Aug 13 21:22:55 kaperfahrt kernel: st0: Illegal block size.


--------------

>mt setblk 0

root@kaperfahrt:~/bin# xfsdump -o -l 0 -v trace -F -L test -M test -f 
/dev/tape /dev/hdg1
xfsdump: version 3.0 - Running single-threaded
xfsdump: WARNING: most recent level 0 dump was interrupted, but not 
resuming that dump since resume (-R) option not specified
xfsdump: level 0 dump of kaperfahrt:/mnt/d_hdg1
xfsdump: dump date: Mon Aug 13 21:23:41 2001
xfsdump: session id: a96cd865-e050-4e52-883c-d3a657494e28
xfsdump: session label: "test"
xfsdump: ino map phase 1: skipping (no subtrees specified)
xfsdump: ino map phase 2: constructing initial dump list
xfsdump: ino map phase 3: skipping (no pruning necessary)
xfsdump: ino map phase 4: skipping (size estimated in phase 2)
xfsdump: ino map phase 5: skipping (only one dump stream)
xfsdump: ino map construction complete
xfsdump: estimated dump size: 11599985152 bytes
xfsdump: preparing drive
xfsdump: variable block size tape drive at /dev/tape
xfsdump: WARNING: media may contain data. Overwrite option specified
xfsdump: dump size (non-dir files) : 0 bytes
xfsdump: NOTE: dump interrupted: 0 seconds elapsed: may resume later 
using -R option
root@kaperfahrt:~/bin#

(no syslog entry)