Re: Software Raid 5

My apologies, I should have been more specific.  I have also come across
a number of posts touching on software raid.  I was referring to
inter-node software raid IE:

md0
	/dev/1/hda2
	/dev/2/hda2
	/dev/3/hda2
	/dev/4/hda2

Where loss of node 1 would not constitute loss of the cluster.  If this
is not possible with the md code that is in the kernel due to the
underlying architectural changes, is it possible to do this with AOE
devices?


Larry Brown

-----Original Message-----
From: Ed King [mailto:[email protected]] 
Sent: Monday, June 19, 2006 1:27 PM
To: Brown, Larry
Cc: [email protected]
Subject: Re: [SSI-users] Software Raid 5

If you want the root to be fault tolerant, a standard debian
installation allows this (Sarge 3.1).

We partition each drive with a small boot partition (~50MB) , some swap
space (1GB) and the rest being allocated for RAID.

The installer is told that the first drive, first partition is mounted
as boot, the other primary partitions on the other drives are not
designated to be mounted (the debian installer can't have more than one
drive mounted to the boot point).

The installer allows the creation of the raid, and we flag that as
mounting as the root filesystem -- it gives us a very large software
raid, and on the faster processors can actually give better performance
than hardware raids.  The boot partition never changes (unless we
upgrade the kernel) and is small enough so we use dd to copy it over to
the other unused partitions so all the drives are now bootable.

Brown, Larry wrote:
> OK, I'm going to ask a stupid question.  I'm sure I must have run 
> across this in the past but can't find any mention of it now...
>
> Is it possible to allow a small group of nodes to boot to an init node

> where the init node is still running off initrd, mount their disks 
> with software raid, and pivot root over to them allowing the root 
> filesystem to be fault tolerant with software raid 5?
>
> Larry Brown
>
>
>
>
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