If I have 2 tape drives. Can I copy all content from a tape, say A, to
another, say B, on fly? Or I must restore all content on tape A to
disk and archive them to tape B? Appreciated for any reply.

"alex" <shao.tu (AT) gmail (DOT) com> wrote

As always, it depends. If you know which software wrote the original tape
then things are much easier. If it's a Unix/Linux tape you may be able to do
a block level copy of some sort, or use tar or cpio to copy the data. If you
know it's from a certain backup software vendor then maybe you can get an
eval copy of the software and duplicate the tape if it has a copy function.

Last but not least is generic tape copier software. I have written such
software in the past for specific tape drives and there's a couple of
commercial software packages out there that can do that.

Rob

On 5¤ë17¤é, ¤U¤È6®É30¤À, "Rob Turk" <wipe_this_r.t... (AT) chello (DOT) nl> wrote:
Thanks for reply. Follow your descriptions. The problem I ran into
should be easy since the content of the original tape was archived via
star utility. I had be been tried using pipe, like star -x ... | start
-c ..., to achieve that. But it didn't work. star reported that it
cannot handle such condition. So I really don't know how to do that
this time. Can you give me some directions? The tape library I'm using
is Sun StorEdge C4 and it is attached to a linux box running RHEL AS4.
Thanks again.

On May 17, 11:28 pm, alex <shao... (AT) gmail (DOT) com> wrote:
Did you try the block level copy, as Rob suggested? For disks on
Linux, this generally works:

dd if=/dev/hda of=/dev/hdb

Of course, use the right nodes under /dev for your tape drives :^)

alex <shao.tu (AT) gmail (DOT) com> wrote:
This would have unpacked all data (star -x) and then created a new
archive (star -c). You want to copy the tape "as is", using the block
level copy he mentions.

The standard Linux/Unix way to copy things to/from devices is dd.
Since you know it's written with star it's ought not to be THAT
complicated, it avoids most of the really thorny problems with more
advanced tape users (segment marks and multiple independent tape
sections).

You MAY need to match star's block size used when writing the tape,
default is 10 kB but as they mention in the manpage a bigger number is
better due to generally better performance...

OTOH even if you get the block size wrong it looks like the -B option
may well allow it to work.

Also, if there's multiple backups on the tape you need to use the
"non-rewinding" tape device, and run dd for each backup! Figuring out
when there's no more data isn't exactly hard, but at that point I
really suggest getting someone to help you which knows how to do
things like this instead of trying to do it yourself!

So, best guess with default block size and only one backup:

dd if=/dev/TAPE1 of=/dev/TAPE2 bs=10k

Where TAPE1 is the (i)nput tape (original) and TAPE2 is the (o)utput
tape, ie the copy. Use "man dd" for more information and options.


Just make really sure you're putting the right tape into right tape
drive, so you're not overwriting the original with an empty file :-)

I'd recommend testing the "input" tape with star first, the rewind and
run the copy.

On 5¤ë20¤é, ¤W¤È12®É54¤À, Torbjorn Lindgren <t... (AT) none (DOT) invalid> wrote:
I appreciate all you guys. dd does work for my purpose. Thanks again.