Re: Switch running System to RAID-1
On Sat, Dec 22, 2007 at 01:05:31AM -0500, Scott Gifford wrote:
> alexandrus <deralex84-forum@yahoo.de> writes:
>
> > Hi,
> > I just figured that our complany's server was running on JBOD with 2 HDs,
> > one of them entirely unused (d'oh!). Of course I would like to have it as
> > RAID 1.
> >
> > Now, I built an Array from the HD in use and know how to make it bootable,
> > but I suppose I have to make some changes to the boot-config before it will
> > run as before. Which could these be?
>
> If you're using software RAID, the boot device will now be "/dev/md?".
> You will need to configure your boot loader (grub or LILO) to boot
> from that partition, make sure your initrd loads all of the right
> modules, and change your /etc/fstab to mount the md devices instead of
> the hard drive devices.
For Etch's install, grub can't boot from a raid array as /dev/md?. It
can read a single disk, so if its a raid1 array, both (all) partitions
are the same. My /boot is on raid1 and my Grub menu.list has entries
for /dev/sda1 and /dev/sda2. I have installed grub onto the MBR of both
disks so that I can still use a menu item to boot if one drive is
missing.
>
> I have found this to be surprisingly tricky to get right on the first
> try, so make sure you have a boot disk handy.
>
> Creating a configuration file for the RAID devices seemed to help
> mkinitrd/yaird figure out that it needed the RAID modules. grub
> seemed to have better support for RAID than lilo, although it was a
> bit "magical" and hard to debug when it didn't work properly.
>
> At one point I found some useful instructions with google, but I can't
> seem to find them now. Still, there seem to be some useful howto
> guides that should get you pointed in the right direction.
Once GRUB boots, its easiest to use filesystem lables for device names
for the kernel and in fstab. Then the kernel can hunt and find what it
needs.
LVM over top of raid also works a treat.
Doug.
Reply to: