[KLUG Members] Question on RAID

[Mike Williams]

>
>
>From: "Sanjay Chigurupati" <Sanjay.Chigurupati@lntinfotech.com>
>Date: Thu, 13 Nov 2003 11:11:25 +0530
>Subject: [KLUG Members] Question on RAID
>Reply-To: members@kalamazoolinux.org
>
>Hi,
> I am implementing a Software RAID (level 1 -mirroring)  for a server,
>using two hard disks. Is it necessary that we put boot partition on  a RAID
>partition?
>
>I have currently set /home, / and /var on raid partitions.  Purpose is to
>provide availability for, ftp documents uploaded for users,  ftp software
>as test setup.
>
>All suggestions welcome.
>
>Sanjay
>

You could.  I think most bootloaders will happily use a mirrored 
partition.  If not, since /boot doesn't change very often, you have 
another option.  Create a backup /boot on another drive, and put a 2nd 
entry in GRUB or LILO that will boot from it.  Have a cron job that runs 
once a week or so that synchronizes them.  Also, considering that your 
bootloader is going to be installed on one of the drives that you're 
worried about failing, a boot disk is highly recommended.

If you're going to use software RAID, though, you're going to want to 
brush up on how you fail and replace a drive in the mirror:  
"raidsetfaulty /dev/md0 /dev/hda1"  ... shutdown and swap ... 
"raidhotadd /dev/md0 /dev/hda1".   For reasons I don't yet understand, 
most of your RAID management commands are softlinks to /sbin/raidstart.  
Did I mention the documentation for this is basically nonexistent?

As a side note, this same trick (except for the bootdisk part) works on 
Windows servers too if you've got somebody who's too cheap to buy a real 
RAID card!