Re: software RAID vs hardware RAID


Subject: Re: software RAID vs hardware RAID
From: Joshua J.Kugler (isd@as.uaf.edu)
Date: Fri Mar 14 2003 - 12:43:43 AKST


On Friday 14 March 2003 12:22, Damien Hull wrote:
> As for /root needing to be on the array, yes. It needs to be on the
> array because you need to be able to boot off of it.
>
> If /root or /boot, depending on how you set it up, isn't on the array
> and one drive fails then you loose your kernel. No kernel means no more
> system.

OK...I'm going to try to tread carefully, because I may not know what I'm
talking about. Your RAID array does not need to include your root partition.
 You can boot off a system drive, and then mount your RAID array as you're
going through the boot process.

Just found this via google:
http://en.tldp.org/HOWTO/Software-RAID-HOWTO.html

According to the howto (below), "The boot device MUST be a non-raided
device." It seems from the configuration that a RAID device just becomes a
partition, as far as fstab is concerned, you you could do something like this:

/dev/hda5 / ext2 defaults 1 1
/dev/hda1 /boot ext2 defaults 1 2
/dev/md0 /home/ ext2 defaults 1 1

Also, keeping your /, or /usr, or /whatever separate from your RAID device
would making stopping RAID for repair/maintenance that much easier, as you
can stop all the programs using /home, but it's a lot harder to stop the
programs using / without a boot to a maintenance CD. :)

Does that make sense?

Have fun. :)

j----- k-----

-- 
Joshua Kugler, Information Services Director
Associated Students of the University of Alaska Fairbanks
isd@asuaf.org, 907-474-7601

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