backing up /sys

Bob McClure Jr robertmcclure at
Tue Jun 28 23:39:31 UTC 2005

On Tue, Jun 28, 2005 at 03:12:02PM -0700, Rick Stevens wrote:
> Bob McClure Jr wrote:
> >
> >I'm still deciding whether I want to continue just backing up root,
> >home, etc, var, and usr/local, and restore that on to a freshly
> >installed system, or to make a complete backup from which I can
> >restore to a bare-metal (or possibily minimally installed) system.
> Uhm, gee.  I back up each filesystem individually with exclusions.
> I do this using two different methods: amanda (to DLT tapes) and using a
> fairly complex "find" command to build ISO images for burning to DVDs.

I have a client that backs up to tape and to alternaing partitions on
a removeable IDE drive (of which he has two that he swaps
occasionally).  The latter is set up to be bootable.  I thought that
was a little overkill, but I don't any more.

> >You won't be surprised at the reason for my sudden interest in this.
> >Yeah, two disk crashes in the last month.
> Wow!  Bad hardware, power spikes or the family dog lifting his leg on
> the system?

The first was an antique 8G drive that started whining about a week
before it totally augered in.  I replaced it with a disk with FC2 on
it from my file server that I'd replaced with a big 250GB drive, then
backfilled it from backups.

The other was a drive I'd bought three weeks before from a big
electronics bargain house.  The box had been opened so the price was
reduced, but it was the only one there of the size and type I wanted.
Needless to say, after returning that drive, I won't be darkening
their door again.  The old drive had not yet been recycled, so I put
it back in.  That's when I found my backup tapes were fubar.  But I
had good incrementals on another machine, so I got most of it back.

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

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.

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

> ----------------------------------------------------------------------
> - Rick Stevens, Senior Systems Engineer     rstevens at -
> - VitalStream, Inc.              -
> -                                                                    -
> -      Do you know how to save five drowning lawyers?  No?  GOOD!    -
> ----------------------------------------------------------------------

Bob McClure, Jr.             Bobcat Open Systems, Inc.
robertmcclure at
God doesn't have (or need) a Plan B.

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