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From: "K. Posern" <quickhelp@gmail.com>
To: linux-raid@vger.kernel.org
Subject: intel fakeraid (imsm) linux kernel support
Date: Tue, 17 Aug 2010 12:19:56 -0400	[thread overview]
Message-ID: <4C6AB6AC.40904@gmail.com> (raw)

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Hi all,

I am trying to find out if it is possible to:

	a) Have the linux kernel autodetect / auto-assemble the fakeraid (to 
avoid having an initrd (for speed and KISS))

	b) Boot linux kernel from a fakeraid this: grub2? lilo? ... anything?	

About (a):
Is it possible to autodetect any intel fakeraid (imsm)?
If yes: What RAID-Levels are supported? Especially what would I need to 
do to get my RAID-0 auto-assembled?
If no: Are there plans?

About (b):
What boot-loader support to assemble the intel fakeraid to read the 
kernel from it - e.g. are able to assemble the /boot partition on the 
RAID (especially: level 0)?
According to this wiki entry:
	http://wiki.neuralbs.com/index.php/Gentoo_Quick_Install_notes#GRUB2
grub2 should support imsm (but grep for imsm in the Bazaar checkout does 
not yield any hit) <<< I also contacted the grub2 mailing-list for 
clarification
I learned today that Ubuntu seems to be able to boot from a RAID-0 with 
grub2 (v1.98-1ubuntu7) and seemingly installed to /dev/mapper/isw_*.
So far I only tried to install vanilla grub 1.98 to the mdadm v3 devices 
/dev/md12[67], without success.
In the documentation of grub2 (afaik) they don't distinguish between 
mdadm/dmraid software raid, they just state that grub2 works with 
software raid.

Side-Question:
To be able to have the kernel auto-assemble / autodetect any [e.g. 
mdadm] linux software RAID-0 you need *partions*, right?
--> You can't assemble a software raid-0 using two complete drives:
	/dev/sda
	/dev/sdb
But you need to create e.g.:
	/dev/sda1 <<< type set to FD
	/dev/sdb1 <<< type set to FD


It would be great and very kind if someone could clarify these things 
for me (just a link to read the answers somewhere would work too ;).
Thanks a lot!


Knuth

P.S.:
I adore Intels engagement for linux. Unfortunately is there no website 
(yet?) "intellinuxraid.org" (like there is: intellinuxgraphics.org).

The only official information from intel (google: intel raid linux) I 
could dig up so fare states: imsm is supported with mdadm >=v3 and 
dmraid >=v1. That leaves a lot of questions (eg. I never saw any details 
on how the intel software raid format works - e.g. I noticed that the 
first physical device of my RAID-0 seems to have the primary paritions, 
all the other RAID-0 devices are unpartitioned).



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             reply	other threads:[~2010-08-17 16:19 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-17 16:19 K. Posern [this message]
2010-08-17 17:26 ` intel fakeraid (imsm) linux kernel support Dan Williams
     [not found] <4C69D525.4060404@gmail.com>
2010-08-17 16:49 ` [mdadm git pull] "--assemble --scan" support for imsm Dan Williams
2010-08-18 17:49   ` intel fakeraid (imsm) linux kernel support K. Posern

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