backing up /sys

[Bob McClure Jr]

On Wed, Jun 29, 2005 at 11:36:10AM -0700, Rick Stevens wrote:
> Bob McClure Jr wrote:
> >On Tue, Jun 28, 2005 at 03:12:02PM -0700, Rick Stevens wrote:
> >
> >>Bob McClure Jr wrote:
> >>
> > <snippage>
> >I discovered that when I run
> >
> >  mt <any_command>
> >
> >it returns immediately, but the tape goes on to do the function,
> >presumably satisfactorily.  So my backup script says, in part,
> >
> >/bin/mt rewind
> >/bin/mt erase
> >/bin/mt rewind
> >/bin/mt reten
> >echo "backup started at `date`" > $tempfile
> >if find $dirlist -mount -depth | cpio $cpio_opts > $TAPE 2>>$tempfile
> >then
> >  .
> >  .
> >  .
> >
> >So it blows through the mt commands and rolls right in to the cpio
> >operation, and I presume the tape starts recording mid-stream.  I
> >pulled the contents of the tape to a file, and ran "file <filename>"
> >and it said "data".  The tape is a Travan-4 in an IDE tape drive using
> >the ide-scsi module.  The device is /dev/nst0.
> 
> Uh, hmmmm.  Have you tried /dev/st0 instead?  Sometimes the "n" does
> do an immediate return.  The ide-scsi may also be an issue.  I tend to
> use real SCSI drives.  You can get DAT drives pretty cheap now.  DLTs
> are available on E-Bay pretty cheap, too (the tapes aren't cheap, but
> they're reasonable).

Nah.  I have a CD/DVD burner, now, so I'm going to a combination of
CDs or DVDs for full backup and incrementals to a disk on a different
machine.

> >I'm going to run a test tonight, having done the mt steps manually,
> >and have it go straight to the cpio, and see if I get a recognizable
> >tape.

Well, the answer is, I didn't.  I checked it using

  cat $TAPE | cpio -it

and all it did was "shoeshine" the tape with no output.
Interestingly, /var/log/messages says,

Jun 29 14:21:59 bobcat kernel: st0: Error with sense data: <6>st0: Current: sense key: Illegal Request
Jun 29 14:21:59 bobcat kernel:     Additional sense: Invalid command operation code
Jun 29 14:22:54 bobcat kernel: st0: Error with sense data: <6>st0: Current: sense key: Illegal Request
Jun 29 14:22:54 bobcat kernel:     Additional sense: Invalid command operation code

Doesn't that look like a kernel (module) bug?

I'd blame the tape drive, but I have another one like it in another
machine and it does the same thing.

> Also try the /dev/st0 device and see if it behaves differently.
> ----------------------------------------------------------------------
> - Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
> - VitalStream, Inc.                       http://www.vitalstream.com -
> -                                                                    -
> - Linux is like a wigwam...no windows, no gates...and apache inside! -
> ----------------------------------------------------------------------

Cheers,
-- 
Bob McClure, Jr.             Bobcat Open Systems, Inc.
robertmcclure at earthlink.net  http://www.bobcatos.com
God doesn't have (or need) a Plan B.