[lug] Backup to 2nd HD with dd & rsync?

[Nate Duehr]

Inline...

> -----Original Message-----
> From: lug-admin at lug.boulder.co.us [mailto:lug-admin at lug.boulder.co.us]On
> Behalf Of Peter Hutnick
> Sent: Sunday, January 26, 2003 2:34 AM
> To: lug at lug.boulder.co.us
> Subject: Re: [lug] Backup to 2nd HD with dd & rsync?
>
> Nate Duehr said:
>
> > SCSI handles the MBR differently with the whole initial ramdisk
> > (mkinitrd) thing... the IDE probably won't boot properly after a dd from
> > the SCSI, but never tried it.
>
> The initial RAM disk adn SCSI aren't related in any technical way.  You
> probably have the impression that they are because distro kernels tend to
> have IDE support built in and SCSI support as modules on an initial RAM
> disk image.  This is because any given SCSI driver is far less common than
> the IDE driver.  IOW this relates to packaging, not how the kernel works.

Interesting, I never realized that... I don't dink around much with the
low-level boot process, but I guess you're saying that if you have a kernel
pre-compiled with your SCSI driver in it monolithically, you don't need to
do the bootstrapping gunk from an initial Ramdisk... that makes sense.
Hmm... never realized that.

> As to making a backup, I have done this with rsync from one IDE disk to
> another IDE disk of a different type.  Using dd is likely to cause far
> more problems than it solves for this task.  If you want true backups try
> dump.  If you want what I call a "cold mirror" run rsync out of cron.

Agreed here.  I only mess with dd on *exactly identical* hardware.

> One system I set up this way excluded /etc/fstab on the backup.  I set up
> a floppy and rdeved it to the backup drive.  I manually edited the backup
> copy of /etc/fstab.  That floppy could then be used to roll the system
> back to the last rsync.

Ahh... interesting tactic.

> The nice thing about this is that it is very easy to recover a file from
> the rsync backup; just mount the disk and use normal filesystem tools
> (i.e. cp).  Beats the hell out of tapes for an "oops" type restore.

Yeah, tape sucks, but it's nice to know everything's on tape if you need
it... Catch-22.

Nate