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Kernel 2.6 installation support for fakeraid HBAs

Rick Moen [rick at linuxmafia.com]
Tue, 18 Jul 2006 16:15:16 -0700

You know, I personally think it'd be perfectly OK to publish threads like these I'm forwarding as TAG threads, in the magazine. That is the main reason I keep forwarding them.

From: "magnate" <chrisc@dbass.demon.co.uk>
To: TAG <tag@lists.linuxgazette.net>
Newsgroups: comp.os.linux.setup
Subject: Debian installer does not recognise ataraid array
Date: 18 Jul 2006 03:14:30 -0700
I have two SATA HDs on a Silicon Simage 3112 RAID controller. This is known as "fakeraid" or "ataraid" because it's not a proper hardware RAID controller, it just buggers about with on-the-fly address translations in the controller's BIOS. So it's a bit like software RAID - and indeed inferior to Linux software RAID - but this is a dual-boot box, which is why I'm using it. (Honestly, it makes Windows a lot faster, like 50%+.)

So, I want to install Debian on it. I managed it under 2.4 by manually coaxing the medley.o module into place, to recognise the array and let me install on it. On the way I found and reported several bugs: a conflict between siimage.o and via82cxxx.o (which is still unsolved in kernel-source-2.4.27), the fact that ataraid modules were not loaded by the installer, and the fact that medley.o was missing from the mkinitrd script, which meant that I couldn't boot after the install!

I'm not sure if that second one is solved yet, but it doesn't matter because this time I'm trying to install 2.6 (I am reinstalling rather than upgrading because I made a ton of changes to the partition structure). I know that 2.6 doesn't use the medley module, and that all the fakeraid stuff is dealt with by something called the device mapper, and a user-space tool called dmraid.

Unfortunately I don't know any more than that, like how they work. When I use the latest Debian installer CD, it boots 2.6 and finds all my hardware and offers me sda and sdb as my HDs - it completely fails to notice the fakeraid array.

Yes I have brought this to Debian's attention, but I'm asking here because I really need to just know a few more basics about ataraid handling in 2.6.x and the device mapper - can anyone point me towards a HOWTO or idiot's guide for that?

Grateful also for any other advice on how to diagnose this problem. I presume that the low-level hardware driver (sata_sil.o in this case) is still needed - this is what's finding sda and sdb. But I don't know what to do once that's loaded to find the ataraid array, and therefore I don't know how to find out where the Debian installer is going astray.

Rgds, CC

From: Michael Heiming <michael+USENET@www.heiming.de>
To: TAG <tag@lists.linuxgazette.net>
Newsgroups: comp.os.linux.setup
Subject: Re: Debian installer does not recognise ataraid array
Date: Tue, 18 Jul 2006 22:13:55 +0200
User-Agent: tin/1.9.1-20060409 ("Benmore") (UNIX) (Linux/2.6.17-mh (i686)) tinews.pl/1.1.7
In comp.os.linux.setup magnate <chrisc at dbass.demon.co.uk>:

> I have two SATA HDs on a Silicon Simage 3112 RAID controller. This is
> known as "fakeraid" or "ataraid" because it's not a proper hardware
> RAID controller, it just buggers about with on-the-fly address
> translations in the controller's BIOS. So it's a bit like software RAID
> - and indeed inferior to Linux software RAID - but this is a dual-boot
> box, which is why I'm using it. (Honestly, it makes Windows a lot
> faster, like 50%+.)
> So, I want to install Debian on it. I managed it under 2.4 by manually

Haven't used any of those fakeraid controllers, but from the following URL (great job Rick!):

http://linuxmafia.com/faq/Hardware/sata.html

It looks like you are perhaps just using the wrong distro? For some desktop I'd try out FC 5 and see if this works better.

This URL seems to suggest it:

http://tienstra4.flatnet.tudelft.nl/~gerte/gen2dmraid/

Red hat's Fedora Core can be used to install Linux on your RAID set. Download Fedora Core here: http://fedora.redhat.com/

[..]

Good luck

-- 
Michael Heiming (X-PGP-Sig > GPG-Key ID: EDD27B94)
mail: echo zvpunry at urvzvat.qr | perl -pe 'y/a-z/n-za-m/'
#bofh excuse 443: Zombie processes detected, machine is haunted.
From: Rick Moen <rick@linuxmafia.com>
To: TAG <tag@lists.linuxgazette.net>
Subject: Re: Debian installer does not recognise ataraid array
Newsgroups: comp.os.linux.setup
Organization: If you lived here, you'd be $HOME already.
User-Agent: tin/1.8.1-20060215 ("Mealasta") (UNIX) (Linux/2.4.27-2-686 (i686))
Date: Tue, 18 Jul 2006 18:35:32 -0400
Michael Heiming <michael+USENET at www.heiming.de> wrote:

> Haven't used any of those fakeraid controllers, but from the
> following URL (great job Rick!):
> 
> http://linuxmafia.com/faq/Hardware/sata.html

Much obliged, my good sir! I do try; but you're welcome to flatter me any time. ;->

New to my stable of documentation, but very similar to the above: http://linuxmafia.com/faq/Hardware/sas.html

(Serial Attached SCSI is doing to Ultra320 what SATA did to PATA -- except a lot faster. SAS-chipset support is starting to be a real issue with Linux distro installer refreshes.)

-- 
Cheers,      English is essentially Pictish that was attacked out of nowhere by
Rick Moen    Angles cohabiting with Teutons who were done in by a drunk bunch of
rick at linux   Vikings masquerading as Frenchmen who insisted they spoke Latin and
mafia.com    Greek but lacked the Arabic in which to convey that. -- Bill Hammel
From: Rick Moen <rick@linuxmafia.com>
To: TAG <tag@lists.linuxgazette.net>
Subject: Re: Debian installer does not recognise ataraid array
Newsgroups: comp.os.linux.setup
Organization: If you lived here, you'd be $HOME already.
User-Agent: tin/1.8.1-20060215 ("Mealasta") (UNIX) (Linux/2.4.27-2-686 (i686))
Date: Tue, 18 Jul 2006 19:07:21 -0400
magnate <chrisc at dbass.demon.co.uk> wrote:

> I have two SATA HDs on a Silicon Simage 3112 RAID controller. This is
> known as "fakeraid" or "ataraid" because it's not a proper hardware
> RAID controller, it just buggers about with on-the-fly address
> translations in the controller's BIOS. So it's a bit like software RAID
> - and indeed inferior to Linux software RAID - but this is a dual-boot
> box, which is why I'm using it. (Honestly, it makes Windows a lot
> faster, like 50%+.)

[snip details of your plan to try again using the Debian d-i installer's "bf2.6" installation flavour]

Chris, I read your post last night, and at the time was very impressed with your thorough approach to both the testing process and recounting of same on this newsgroup. Like Michael Heiming, who kindly posted the link to my Linux on SATA page, I have little practical experience with fakeraid controllers -- and just about everything I know on the subject is already on the aforementioned page.

> Yes I have brought this to Debian's attention, but I'm asking here
> because I really need to just know a few more basics about ataraid
> handling in 2.6.x and the device mapper - can anyone point me towards a
> HOWTO or idiot's guide for that?

I've not yet found one, and I've really looked extensively (though not lately). In addition to the dmraid resources linked from my SATA page, please see if the udev-related entries on http://linuxmafia.com/kb/Kernel are any use to you -- since hotplug, udev, sysfs, and the devicemapper all work closely in 2.6.

Anyway, my understanding is that the ataraid software layer is 2.4-specific, and dmraid is ataraid for 2.6. (You may have meant simply "Linux parsing of ATA fakeraid disk semantics", in which case no criticism intended, and I'm just being careful to disambiguate.)

> Grateful also for any other advice on how to diagnose this problem. I
> presume that the low-level hardware driver (sata_sil.o in this case) is
> still needed - this is what's finding sda and sdb.

Correct.

> But I don't know what to do once that's loaded to find the ataraid
> array, and therefore I don't know how to find out where the debian
> installer is going astray. 

My impression is that you're not missing anything, except the extremely high likelihood that the current Debian installer ("d-i") doesn't have dmraid support in the installation kernel. Now, what you could do is to install some other leading-edge distribution, e.g., FC5, and then do a chroot installation of Debian, using the other distro's infrastructure support for dmraid to accomplish the job. You'd then compile a dmraid-supporting kernel inside the chroot jail before rebooting.

(See: "Installers" on http://linuxmafia.com/kb/Debian on how to do chroot installs. It's actually pretty easy, and interesting to do.)

See also: http://www.redhat.com/archives/ataraid-list/2005-July/msg00014.html

The existence of this "udeb" package suggests that my suspicion about d-i is correct: Such packages are useful in constructing custom installer images. (There are lots of such custom installer images catalogued on the aforementioned "Installers" page; might be one with dmraid support.) http://packages.debian.org/unstable/debian-installer/dmraid-udeb

That package should not be confused with userspace package "dmraid", which is the glue to control fakeraid operations via devicemapper: http://packages.debian.org/unstable/admin/dmraid

Good luck.

-- 
Cheers,      English is essentially Pictish that was attacked out of nowhere by
Rick Moen    Angles cohabiting with Teutons who were done in by a drunk bunch of
rick at linux   Vikings masquerading as Frenchmen who insisted they spoke Latin and
mafia.com    Greek but lacked the Arabic in which to convey that. -- Bill Hammel


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