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Re: software raid



hi ya lucas

On Sat, 13 Dec 2003, Lucas Albers wrote:

> I've been trying to get debian stable working with software raid using
> various documentation.

collection of um
	http://www.1U-Raid5.net

> If you can think of any good software raid (running on your root partition)
> documentation for debian STABLE please send it over.

"good sw raid" is already part of the linux kernel..
you dont need anything else ... other than to turn on the raid options
in the kernel  and create your raid config files

> I don't want ANY testing, as these systems are for production systems.

good, but you still hae to test the new raid setup before it 
goes to production ...

minimum testing process..
	http://www.1U-Raid5.net

	- turn off each disk and write data and reboot and watch it resync

> I'm trying to setup a debian stable machines to run with software raid for
> additional redundancy.

good idea
	- do you raid just the data .. or the OS too ?? ( root raid )

	- do you use raid1 ( mirror ? )

	- if you use raid5 ( you supposedly cannot boot off / that is 
	raid5 .. but i think if you have a proper initrd, it works )

and redundancy also comes from monitoring the raid setup 
	- lots of scripts you can write to monitor the raid system

> I would like to determine how to setup software raid on an new system, and
> how to convert an existing system to use software raid.

for setup of a new system ( the right way?? )
	- make sure the partition type is FD(raid) not 82(linux)

	- install the / system as root  ( unfortunately, fortunately,
	redhat/suse makes installing onto hda/hdc trivially simple )

	- debians new installer should allow for root raid installs

	- simpler/faster/easier to copy the exisitng data to a backup data

	or just start with 2 fresh disks and leave the current disk alone
	and retire it after your new raid setup is testing/working and
	been running a few months

	- new disks is $70 or less for 40GB... thats 30 minutes of time
	or less ... ( cheaper/faster to get to 2 new disks )

- for existing systems ..
	- boot a standalone media ...
	- partition both target disks as FD partition types
	- config both disks and format
	- install as usual

- make sure your final raid config is:

	# allow you to boot off hda or hdc
	#
	boot=/dev/md0
	...

	# root raid 
	root=/dev/md0


> I'm aware of the documentation in raidtools2 and mdadm.

good 

> I have read most of the documentation...but they lack items.

yup.. lack the key problems ...

> I can recompile the kernel; use a new kernel if necessary.

since these are for production .. you should to it the right way ...
vs copying an existing system to a 2nd disk  ( it's NOT raid
until you get the partition type to be "raid" )

raid when properly setup will be able to boot and keep running
even if the any 1 other disk is pulled out of your system

c ya
alvin




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