Re: [PARPORT] epat pt driver with HP colorado 8GBe parallel port tape drive

J Scott Berg (
Tue, 8 Sep 1998 13:52:30 -0500 (EST)

On Tue, 8 Sep 1998, Lynton Reed wrote:

> mt -f /dev/pt0 status
> and I get
> pt0: HP COLORADO 8GBe, master, blocksize 512, 4007 MB
> pt0: Unimplemented ioctl 0x801c6d02
> /dev/pt0: Invalid argument

The only mt operation that is implemented for the pt driver is the
rewind operation. Don't sweat this one.

> trying to run the taper package results in similar errors (and others about
> mt_op )
> undeterred I tried to
> tar -cf /dev/pt0 /testdata # few meg only.
> which worked !!!! I was then able to untar and restore these files.
> I then attempted a full backup (except /proc )
> tar -zcf /dev/pt0 --exclude /proc / # is there a better way ?
> but when I try to list the archive get
> tar -tf /dev/pt0
> pt0: HP COLORADO 8GBe, master, blocksize 512, 4007 MB
> tar: Hmm, this doesnt look like a tar archive
> tar: Skipping to next file header
> tar: Skipping to next file header
> tar: Skipping to next file header
> .................... ad infinitum

The reason it doesn't think it's a tar archive is that you used the
'z' flag in creating the archive, thus compressing it, while you
didn't use the 'z' flag when extracting it.

The reason for the infinite number of "Skipping to next file header"
messages is probably the unimplemented mt operations again: "skip to
next filemark" is one of those mt operations. This won't be an issue
if you use the right flags on tar.

By the way, I recommend against using the compressed option, since if
one block on the tape gets hosed, then everything after that on the
tape is hosed as well.

I typically use GNU cpio with the crc format, and find to get the file
list. This involves a fair amount of disk overhead, though, which may
be slowing down my backups. You may consider using bzip for
compression if you need it, since it claims to allow some recovery of
data following bad blocks.

See my previous notes about using that 8GB Travan drive as well.

                                -Scott Berg

J. Scott Berg                                 Phone: (812) 855-5465
Indiana University Cyclotron Facility         FAX:   (812) 855-6645
2401 Milo B. Sampson Lane                     email:
Bloomington, IN  47408-1398

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