Re: [Dump-users] RE: Dump HOWTO

[Bernhard E. <be...@be...>]

li...@li... wrote:
[...]
> One important remark, though: I run dump remotely (using ssh)
> and experienced several inconveniences/problems:
> 
> -- If I don't set up a .rhosts (so that ssh prompts for a passwd)
> then somehow it seems that dump has grabbed stdin, and won't pass
> on the password to ssh.  So the only way to dump remoely is to
> set up a .rhosts file (yuck).

Can't verify it: (there's no ~root/.rhosts on apollo)

# ssh apollo "/sbin/dump 0af - /" | dd obs=32k of=$TAPE
root@apollo's password: 
  DUMP: Date of this level 0 dump: Tue Jun 27 09:59:30 2000
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /dev/hda6 (/) to standard output
  DUMP: Label: none
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 59977 tape blocks.
  DUMP: Volume 1 started at: Tue Jun 27 09:59:31 2000
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: Volume 1 completed at: Tue Jun 27 10:01:33 2000
  DUMP: Volume 1 took 0:02:02
  DUMP: Volume 1 transfer rate: 495 KB/s
  DUMP: 60420 tape blocks (59.00MB)
  DUMP: finished in 122 seconds, throughput 495 KBytes/sec
  DUMP: Date of this level 0 dump: Tue Jun 27 09:59:30 2000
  DUMP: Date this dump completed:  Tue Jun 27 10:01:33 2000
  DUMP: Average transfer rate: 495 KB/s
  DUMP: DUMP IS DONE
120840+0 records in
1888+1 records out

> -- suppose that above problem was solved.  There is then the
> inconvenience that said passwd would have to be entered for
> each invocation of dump (as well as for the mt), which makes
> running from a shell script hard/impossible. Ideally, I'd be
> able to just log in one session, and run the shell script in that
> and have it all exit when done.

Read some man pages about the ssh suite. Generate some RSA keys without
a passphrase, put it into ~/.ssh/authorized_keys (on remote side) and
you won't have to enter a password. Check /var/log/messages.

Don't use the root account on remote side for scripting. Dump just needs
read access to the devices. So choose a user with group read permission
to /dev/sda5, e.g.

> Other than that, it seems to work fine (although ssh on a 486 on
> an old ne2000 ethernet is slowwww at 70kb a sec).

Did you switch off compression along ssh? Maybe your 486 is too slow for
on-the-fly compression what dump grabs off the disks.
(/etc/ssh/ssh_config, /etc/ssh/sshd_config)

> Which brings me to another question:
> How much buffering, if any, does dump do, and is this adjustable?
> At 70kb/sec, the tape drive seems to be doing a lot of
> rewind/preroll/record type back-n-forth tape movement.
> Of course, tape drives are usually happier when you can stream to them
> at thier natural streaming speed.

Do some buffering on your hard disk:

# ssh apollo "/sbin/dump 0af - /" | dd of=/tmp/apollo.dmp
root@apollo's password: 
  DUMP: Date of this level 0 dump: Tue Jun 27 10:05:39 2000
  DUMP: Date of last level 0 dump: the epoch
  DUMP: Dumping /dev/hda6 (/) to standard output
  DUMP: Label: none
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 59977 tape blocks.
  DUMP: Volume 1 started at: Tue Jun 27 10:05:40 2000
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: Volume 1 completed at: Tue Jun 27 10:07:00 2000
  DUMP: Volume 1 took 0:01:20
  DUMP: Volume 1 transfer rate: 755 KB/s
  DUMP: 60420 tape blocks (59.00MB)
  DUMP: finished in 80 seconds, throughput 755 KBytes/sec
  DUMP: Date of this level 0 dump: Tue Jun 27 10:05:39 2000
  DUMP: Date this dump completed:  Tue Jun 27 10:07:00 2000
  DUMP: Average transfer rate: 755 KB/s
  DUMP: DUMP IS DONE
120840+0 records in
120840+0 records out

# dd if=/tmp/apollo.dmp obs=32k of=$TAPE
120840+0 records in
1888+1 records out