[NMLUG] Disk-to-disk copying and booting

[timothyemerick at yahoo.com (Tim Emerick)]

I've been watching this thread and have a similar situation in place.  I have
2 80 gig HD's in place.  Nightly I cp my user files onto the second drive
keeping a 5 day rolling backup.

Have you ever thought of putting in a mirror raid?    I don't think it's a
big deal to pull out the second drive (which should be an exact mirror of the
first drive), pop in the second drive and tell it to sync up.

Having not actually implemented a raid I'm sure I've over-simplified the
process.

If this is not an option then no harm-no foul.

Regards,

Tim Emerick


> > > On Mon, 2004-09-20 at 09:32, Matthew McCleary wrote:
> > > > Hello,
> > > >
> > > > I am trying to implement a disk-to-disk backup scheme on a server.
> > > > It's not the ideal method (I would have chosen a tape backup myself),
> > > > but it's what I have to deal with.
> > > >
> > > > I've got three 146 GB ultra-320 SCSI disks. They are installed in a
> > > > removable drive frame, though I do not think they are hot-swappable;
> > > > thus, when I install or remove one, I have to first take the machine
> > > > down.
> > > >
> > > > One drive has a complete Red Hat 9.0 system installed on it, which is
> > > > essentially one large partition minus a small /boot partition and a 2
> > > > GB swap partition. The disk is designated /dev/sda.
> > > >
> > > > I've been using dd if=/dev/sda of=/dev/sdb bs=1024k (and dd
> > > > if=/dev/sda of=/dev/sdc bs=1024k) to make a carbon-copy of sda onto
> > > > sdb (or sdc). I'm supposed to do a periodic backup of sda --
> something
> > > > like once a month, rotating the two backup drives monthly. Thus we
> > > > would lose at most a month's worth of work, worst-case.
> > > >
> > > > Here, I come to the problem. To make a new backup, I just run the
> "dd"
> > > > command again -- it doesn't care what's on the drive currently, and
> it
> > > > will even overwrite the partition map. Quite nice. The problem,
> > > > though, happens when next month rolls around and I want to make a new
> > > > backup.
> > > >
> > > > If I take the server down and install one of the backup drives in the
> > > > frame, alongside the main drive, and boot it up, Linux freaks. It
> sees
> > > > duplicate /boot partitions (and actually, it would see duplicates of
> > > > all filesystems) and refuses to mount anything it sees a duplicate
> of.
> > > > I *think* it actually boots, but it does not mount all filesystems,
> > > > which of course will cause problems.
> > > >
> > > > The only way I can think to get around it is to first delete the
> > > > entire partition map on the backup drive (essentially, destroy the
> > > > backup) and then install the blank backup disk in the frame, and then
> > > > boot. That seems to be the only way I can get Linux to boot normally.
> > > >
> > > > Problem is, I don't have another server that I can install these
> > > > drives into -- and so the only way I can destroy the partition map is
> > > > by installing the drives in the very server I'm trying to back up --
> a
> > > > "chicken and the egg" problem.
> > > >
> > > > So, I'm appealing to you: what advice would you have for me to go
> > > > about solving this problem? A tape backup is (unfortunately) not an
> > > > option; due to policy I must do disk-to-disk backups.
> > > >
> > > > Thanks,
> > > > Matthew
> > >
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> >
> >
> >
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