Re: RAID 1 setup on woody
Thanks, this is great. A couple of follow-up
questions:
1. How do I get to single user mode without rebooting?
(I know I should already know this.)
2. Do I need to do anything special to copy the
partitions from /dev/hdaX to /dev/mdY? Once I'm in
single user mode can I just "cp -R /dev/hdaX
/dev/mdY"? Or, will I need do something like the HOWTO
suggests for the root filesystem for all the
filesystems:
- create /mnt/newroot
- then:
cd /
find . -xdev | cpio -pm /mnt/newroot
Thanks.
Richard
--- Dave Sherohman <esper@sherohman.org> wrote:
> On Fri, Feb 22, 2002 at 10:32:17AM -0800, Richard
> Weil wrote:
> > I need some help setting up RAID 1 on a fresh
> Woody
> > install. The software is newer than the docs,
> > particularly for Lilo, so any help from those with
> > experience would be most appreicated.
>
> The Software-RAID-HOWTO got me through this one.
>
> > My hda and hdc drives are identical in size. hda
> is
> > divided into multiple partitions -- / (/dev/hda2),
> > /boot (/dev/hda1), /home (/dev/hda5), /usr
> > (/dev/hda6), /var (/dev/hda7). There is nothing on
> hdc
> > yet.
>
> Step 1: Partition hdc just like hda. You should
> probably set your
> partitions to type FD on both drives if you haven't
> done so already.
>
> > If anyone has a similar setup already working, I'd
> > love to see their /etc/raidtab
>
> Just lots of sections that look like:
>
> raiddev /dev/md0
> raid-level 1
> nr-raid-disks 2
> nr-spare-disks 0
> persistent-superblock 1
> chunk-size 4
> device /dev/hdg1
> raid-disk 0
> device /dev/hde1
> raid-disk 1
>
> > and lilo.conf files
>
> Pretty bog-standard, aside from the lines:
>
> boot=/dev/md0
> root=/dev/md0
>
> > with a brief description of how to get it working
> > without deleting anything on hda (i.e.,
> reformating
> > the drive).
>
> 1. Partition both drives identically. Make sure
> that no partitions
> on hdc (except for swap - swap can stripe itself, so
> don't RAID it)
> are larger than the corresponding partitions on hda.
>
> 2. Install on hda.
>
> 3. Create your /etc/raidtab with an md device for
> each non-swap
> partition on hda/hdc. For now, set up the last 4
> lines of each md
> device like so:
>
> device /dev/hdcX
> raid-disk 0
> device /dev/hdaX
> failed-disk 1
>
> Note that the partition on hdc is listed first and
> the partition on
> hda is listed as a failed-disk instead of a
> raid-disk.
>
> 4. Start your RAID devices with raidstart. They
> will all be
> degraded (due to the "failed" partitions on hda),
> but that's what you
> want at this point. Format the md devices with,
> e.g., "mke2fs
> /dev/mdX".
>
> 5. In single-user mode, copy each partition from
> hda to the
> corresponding md device. After copying the root
> partition over, edit
> the copy of etc/fstab on the RAID (i.e.,
> /mnt/etc/fstab) to reference
> the appropriate md devices instead of the partitions
> on hda.
>
> 6. Edit lilo.conf, changing the boot and root
> devices to /dev/md0
> and re-run lilo.
>
> 7. Reboot. When the system comes back up, use
> mount to check
> whether your system is mounted from hda or the RAID
> devices. It
> should now be on RAID.
>
> 8. Change your partition types on hda to FD if you
> haven't already
> done so, change all the failed-disk directives in
> /etc/raidtab to
> raid-disk, and add the partitions from hda using
> raidhotadd.
>
> And you're done. Easy as that.
>
> > - Can I create a single RAID device (md0) that
> > mirrors all of the hda/c, or do I need to create
> > separate RAID devices for each partition(md0, md1,
> > ...,md4)?
>
> I'm not entirely sure whether it's possible to
> create an uber-RAID
> and partition it using the md driver, but separate
> md devices works
> fine.
>
> > - Assuming I need one for each partition, what
> are
> > people's thoughts on skipping / and /boot RAID?
> This
> > is the most intimidating part from reading the
> docs,
> > but it would seem to lessen the value of RAID
> > considerably.
>
> There's no reason that / and /boot can't be RAIDed
> also. If you put
> them on RAID, you'll have to reboot to complete the
> transition, but
> that's no big deal.
>
> > - Is the Boot+Root+RAID Howto still accurate,
> > particularly for Lilo?
>
> Never read it. Like I said, the Software-RAID-HOWTO
> seems to be
> sufficient.
>
> > There's now a RAID boot option in Lilo which I'm
> not
> > sure how it would effect things like boot= and
> root=.
>
> Not familiar with this option, but I've used the
> procedure above
> several times (I've got 3 or 4 systems running
> all-RAID) and it works
> fine with potato's lilo. I can't imagine that
> woody's would have a
> problem with it.
>
> --
> When we reduce our own liberties to stop terrorism,
> the terrorists
> have already won. - reverius
>
> Innocence is no protection when governments go bad.
> - Tom Swiss
>
>
> --
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