Red Hat Topics - Raiding Redhat 7.3

Author

Raiding Redhat 7.3

Bob the milkman

2006-01-19, 5:51 pm

Hi I have a small Redhat server running Redhat 7.3.

It has a 9Gb disk with the following partition layout:

Filesystem Size Used Avail Use% Mounted on
/dev/hda2 8.4G 3.7G 4.2G 47% /
/dev/hda1 45M 8.8M 34M 21% /boot
none 251M 0 251M 0% /dev/shm

I have added a 19Gb hard drive.
I would like to mirror the first drive to the second i.e RAID 1.

I was wondering what steps are required in order to perform this, as i
understand that mirroring / (root) is not straight forward. Is this
even possible?

I have created the same partitions on the second drive ( / & /boot ) so
that they are duplicates of the first drive. Was this necessary?

I would like some help on what steps I need in order to set this up and
if possible what to do if one of the drives fails, how do I get my
system up and working again?

Thanks for help.

Paul.

General Schvantzkoph

2006-01-19, 5:51 pm

On Thu, 19 Jan 2006 07:20:28 -0800, Bob the milkman wrote:

> Hi I have a small Redhat server running Redhat 7.3.
>
> It has a 9Gb disk with the following partition layout:
>
> Filesystem Size Used Avail Use% Mounted on
> /dev/hda2 8.4G 3.7G 4.2G 47% /
> /dev/hda1 45M 8.8M 34M 21% /boot
> none 251M 0 251M 0% /dev/shm
>
> I have added a 19Gb hard drive.
> I would like to mirror the first drive to the second i.e RAID 1.
>
> I was wondering what steps are required in order to perform this, as i
> understand that mirroring / (root) is not straight forward. Is this
> even possible?
>
> I have created the same partitions on the second drive ( / & /boot ) so
> that they are duplicates of the first drive. Was this necessary?
>
> I would like some help on what steps I need in order to set this up and
> if possible what to do if one of the drives fails, how do I get my
> system up and working again?
>
> Thanks for help.
>
> Paul.

Doubtful if you can mirror a 9G drive with a 19G drive. RAID is always
done with identical drives. Frankly I don't know why you would want to
waste disk space doing mirroring when you have such tiny drives. If I were
you I'd use the 19G drive for /home. You should never ever put /home on
the same partition as /, it makes upgrading the system much more difficult
because you can't do a clean install without wiping out your user
directories along with the system files.

Jan Gerrit Kootstra

2006-01-19, 5:51 pm

General Schvantzkoph wrote:
> On Thu, 19 Jan 2006 07:20:28 -0800, Bob the milkman wrote:
>
>
>
>
> Doubtful if you can mirror a 9G drive with a 19G drive. RAID is always
> done with identical drives. Frankly I don't know why you would want to
> waste disk space doing mirroring when you have such tiny drives. If I were
> you I'd use the 19G drive for /home. You should never ever put /home on
> the same partition as /, it makes upgrading the system much more difficult
> because you can't do a clean install without wiping out your user
> directories along with the system files.

Paul,

If you want to do it with software RAID you would need to reinstall your
system, because / cannot be umounted.

I would not go for a mirror but a dual boot.

Create a /etc/fstab on the second disk that refers to the new partitions.

edit your /etc/lilo.conf

run lilo

The bad thing about this senario: no copy of the mbr on disk 2. Has to
do with Intel Architecture, I have never heard that two bootdisks are
allowed.

Kind regards,

Jan Gerrit

Some Other Somebody Else

2006-01-20, 2:46 am

On Thu, 19 Jan 2006 23:28:22 +0100, Jan Gerrit Kootstra
<jan.gerrit@kootstra.org.uk> wrote:

>[...]If you want to do it with software RAID you would need to reinstall your
>system, because / cannot be umounted.
>[...]

Root can be unmounted if you boot from a CD or a floppy or otherwise
from something on another filesystem. I don't know whether that makes
the setup described compatible with RAID, but FWIW....

Bob the milkman

2006-01-24, 7:47 am

Looks like I will rebuild the box with 2 drives and restore from
backup, this is probably my best bet.

Thank you.