Tar to a DLT autochanger

[Jay Gaffney_4]

Hi

What is the best method of writing / reading a tar to an autochanger?
I have an HP A4851A 15 slot tape library. I can use uma to move tapes with the picker, but I can't seem to write or read a tar.
I have tried various devices, as listed in an ioscan -f, but nothing seems to work.

Any help would be appreciated.

THX,

JG

[A. Clay Stephenson]

Since you have the uma utility, you have OmniBack. You can certainly use uma to
move a medium from a slot to a drive. I would put a sleep in the script of about 90 seconds to allow the tape to come 'on-line'. You can then write to the tape using tar, cpio, or fbackup. For a list of devices do an ioscan -C tape -fn. It's possible that your tape device nodes have never been created. You may need to run insf to create them or use mknod to do it manually. I assume that you have the SCSI tape driver installed in your kernel.

After writing, you can then use uma to offl the drive and then a move command to move the tape back to a slot. I actually have one of these old libraries and it works with tar, cpio, and fbackup as long as you have a command like uma to load the drive.

[Michael Tully]

You can also make use the 'mc' command. I think it is easier to use than 'uma'.

Seeing you have uma, you also have Omniback, so why not use it?

e.g.
To move a tape from slot 1 to drive 1.
# mc -p /dev/robot -sS1 -sD1

You could put the whole thing into a script using any backup utility. Make sure you allow enough time for the tape to loaded correctly into the drive so it is on line. A simple 'sleep' of 2 minutes should do the job.

[Jay Gaffney_4]

Can't use Omniback, the tape was written by a command line tar.

I keep getting I/O or tape read errors when using tar. The autochanger light flashes so I think I am accessing the tape, just not reading data...

[A. Clay Stephenson · Accepted solution]

You didn't indicate what drive you have in your library. Your could be equiped with either DLT4000's or DLT7000's. If your foreign tape was written on a DLT8000 (or DLT7000 if your drives are only the DLT4000's) then you are out of luck.

However, your original post indicated that you were unable to write in tar format so you may have other problems.

[Jay Gaffney_4]

DLT4000.

So tapes written by DLT > 4000 can't be read by a 4000?

[A. Clay Stephenson]

No, that dog won't hunt. The tapes are upwardly compatible only. A 7K or 8K can read data written on a 4K but the converse is not true.

[Michael Duthie]

Jay,

You need to use a mixture of the mx (or uma) commands and mt to put the device on or offline before writting.

Of course make sure you have the latest stape & scsi patches.

Mike.