At 02:58 PM 03/18/2000 -0500, Trevor Astrope wrote:
>Is the setup you describe below for a root raid partition as raid1? Sorry,
>I don't have the original message...
Well, yes and no. ;-) I was at the time, trying to do a full root RAID1
but have since decided there are too many possible problems and/or
pitfalls. The /etc/lilo.conf listed below was actually send to me by
someone else as a possible solution, but I haven't yet tried it.
What I'm doing on my 5.2 server at present is making a cold copy of the
boot disk periodically (scheduled via cron) using rsync. All the user data
partitions like /home are on separate physical disks.
What I'll be doing after upgrading to 6.1 is continue to make a cold copy
of the boot disk using cron & rsync. RAID1 mirror /home and /var.
>I tried to make all my partitions raid1 with disk druid during the red hat
>6.1 install, and discovered this isn't possible. I assume what you are
>describing below is to make a separate /boot on each drive and use
>separate lilo.conf files to boot the second drive if the primary fails?
Originally that's what I was trying to do, if somewhat
unsuccessfully. Since both my boot disks are rsync copies, they have the
same /boot directory and lilo.conf. Here's what I do now if I have to boot
from the spare boot disk:
1) Bring down the server cleanly. (Although this may not be possible if
the primary boot disk has failed.)
2) Remove the bad boot disk and put the spare boot disk in it's place. (I
have HP NetServers with hot-swap SCSI drives, accessible from the front, so
it's pretty painless.)
3) Boot from a boot floppy into single user mode and run /sbin/lilo
-v (This way lilo gets installed onto the MBR of the spare boot disk, now
acting as the primary.
4) Edit /etc/fstab so the filesystems on the normally "spare" boot disk
don't get mounted.
5) Comment out the entries to rsync the boot disks.
6) Reboot normally without the floppy. (Note: It may also be possible to
install lilo on the MBR of the spare boot disk ahead of time, in which case
booting from the floppy wouldn't be necessary. I haven't looked into it.)
This may seem complicated or a lot of work, but it's actually pretty
simple, I know it works and it avoids some of the problems I've come across
trying to RAID the root filesystem. I'll probably look into doing it again
in the future, but for now I'm happy with this. With the reliability of
modern disk drives I'm really not as concerned about disk drive
failure. (Or in the event one was failing, hopefully I'd have some warning.)
A word of caution about doing it this way: It's best to set the SCSI ID of
the spare boot disk (assuming you have SCSI) so that it gets recognized
last during bootup. Otherwise if you have to reboot with just the spare
disk you may wind up munging the order of the disks (sda, sdb, etc) and
subsequently hose your device/mount point pairings.
If I wanted to build a really bulletproof server that would continue to run
even if the boot disk failed, I'd probably go with hardware raid.
>A document on the redhat.com site says raiding your swap partitions is a
>bad idea, because you will take a big performance hit if memory needed for
>the raid in case of failure resides in swap.
Correct, you should never mirror swap. The kernel does this automatically
if you have more than one swap partition.
>The machine I am configuring
>is a dual 650 with 640mb of ram, but I thought the machine this is
>replacing (a p3-450 with 256mb ram was enough and it goes a few kb into
>swap). My question here is: if I just use 2 swap partitions that are not
>raided and the memory needed for the raid lives in swap on the primary
>drive that failed, are you not in the same position you were if you raided
>your swap in the first place?
I think having swap get corrupted in the event of a disk failure would
probably be the least of your problems.
HTH
-Eric
Eric Sisler
Library Computer Technician
Westminster Public Library
Westminster, CO, USA
[EMAIL PROTECTED]
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