How to copy one DLT tape to another across network?

[Alex Georgiev_1]

[This message also posted to the HP-UX sys admin forum.]

I need to copy one DLT 7000 tape to another. I have two machines, each with a DLT 7000 drive, each running HP-UX 11. I can't seem to come up with anything more creative than using dd(1).

Anyone have any experience copying tapes from one machine to another? How did you do it?

Is dd going to work across the network? If so, what block size gives the best performance?

Btw, the original tape was created with fbackup(1M).

[Helen French]

Unfortunately, this can't be done. The volumes (tape) created using fbackup command cannot be duplicated by dd command due to the different format that it use. The media duplication with dd is possible with tar, cpio etc.

[Virgil Chereches_2]

I would use a command like this on the system with source tape:
cat /dev/rmt/0mn|remsh dest "cat >/dev/rmt/0mn"
where you must replace with the appropriate device files and the appropriate hostname.
I would recommend you to use a more advanced backup soft for your backup; for example try:
afbackup : http://sourceforge.net/projects/afbackup.
Best regards,
Virgil

[Alzhy]

dd is your only method and it should work this way:

1.\ Count the number of "files" on your source tape:

please check fix syntax..

##/bin/ksh

mt -f /dev/rmt/0mn rew
tstat=0
while true;do
mt -f /dev/rmt/0mn fsf 1
if [ $? ne 0 ] ;then
break;
fi
tstat=($(tstat+1))
done

Echo "No. of files on tape: $tstat"

2.\ On target server, mount tape and do an mt rewind.

3.\ Do your dd:

mt rew
for i in 1 to $tstat;do
dd if=/dev/rmt/0mn | remsh otherserver "dd of=/dev/rmt/0mn

done

I cannot recall the block sizes I use.. try the default first...

[Stuart Whitby]

I'd go with Nelson's recommendations for using dd (though I haven't tried his commands myself). The one thing I would warn you of is that if you're copying full tapes, your copy may fail, no matter how you do it.

Tapes tend to be slightly different lengths. This means that you've got a 50/50 chance of fitting one tape's data onto another. The other potential influence on this is the condition of the tape drive and media which this is being saved to. Dirty drives may not get as good compression as clean ones onto the media, so make sure the drive you're writing from is clean. Reading won't matter, since it'll either read or it won't.