Strange ATARAID format?

Heinz Mauelshagen heinzm at redhat.com
Mon Jan 5 13:58:59 UTC 2009


Am Montag, den 05.01.2009, 07:47 +0000 schrieb Martin Sandaas:
> Hi all!

A happy new year.

> 
> Not sure if this is the right place, as it might also just be a
> hardware issue, an installer issue...or maybe just me ;)
> 
> I've been trying to setup software RAID on this mother board: Asus
> P5Q.  It has (according to lspci) an Intel 82801 SATA RAID controller.
> This controller has 3 settings in the BIOS:
> 1. Use as RAID
> 2. Use as IDE
> 3. Use as AHCI
> 
> I already had a working WinXP install on a RAID0 setup.  But I wanted
> linux, so I went into the BOOT ROM screen (<CTL> + <I> during boot)
> and reset the RAID settings (to single disks).
> Then I went into the BIOS and changed the controller setup to AHCI, as
> I understood it had a performance advantage over IDE mode.
> 
> When I booted Sabayon 4.0 x86_64 LiveDVD, the disks came up normally
> (I thought), but although I was able to change the pratition table,
> nothing got "stuck" after a reboot.
> I then noticed that my previous RAID setup was detected, and activated
> as a VIA "FAKERAID" setup.  And whatever I did, this setup was
> detected and activated.

Because dmraid is being used on it and it relies on ATARAID/DDF1 RAID
metadata signatures and not on any particular transport (eg. IDE, ...)
or mode.

You'd have to run "dmraid -f via -rD" to get rid of them.

Because you mention your Intel chipset and it's isw support, I assume
the disks have been used and set up with a VIA adapter bios before and
now are being reused without ever removing the VIA metadata.

> 
> So I eventually gave up on the AHCI approach, but then I read
> somewhere that the Intel RAID setup was infact using AHCI too.
> I changed the settings back to RAID, and created a striped set on my
> 2x Raptor disks.  And what do you know, this was also detected at
> boot.
> But this time the format was detected as both VIA and ISW, but the
> device-mapper chose ISW (which I think is the right one).

It's not device-mapper per se, it's the mentioned dmraid tool which
discovers it.

With an Intel chipset and Matrix RAID bios, it's going to be isw when
you set up RAID sets via the bios.

You can either "dmraid -f isw -ay" (of course, when not activated as
VIA!) on it to select the isw metadata for activation, or remove the via
metadata as mentioned above ("dmraid -f via -rE") and stay with the
standard "dmraid -ay" in your initrd/initrc.

> 
> So here's my questions:
> 1. Why are both VIA and ISW detected on this chipset (ICH10R), but
> only VIA when setup as AHCI (shouldn't it be ISW if any)?

If there's multiple distinct ATARAID/DDF1 RAID metadata signatures on
the devices, dmraid automatically selects one, unless you use the "-f"
switch.

> 2. And can I somehow force the format to be set as ISW (and suppress
> the VIA format completely)?  (Recompile kernel module without VIA
> support?)

See above: "dmraid -f isw -ay"

> 3. Is the AHCI setup in BIOS supposed to be forced as RAID, or are you
> supposed to be able to use the disks as single disks?  (I can't setup
> any RAID in BIOS when using AHCI)

It's merely the discovery of the metadata signatures independent of any
such mode. If there's accessible signatures and "dmraid -ay" is being
run, it'll discover those and activate mappings.

> 
> As it is now, I'm completely unable to address my disks as /dev/sda
> and /dev/sdb, and have to use /dev/mapper/isw_cbbdijaach_Sabayon (when
> RAID is setup in the BIOS) or /dev/mapper/via_<something> when RAID is
> disabled in BIOS.

If you want to access as single drives:
"dmraid -f isw -rE ; dmraid -f via -rE"


> There's no problems using the current setup (ISW RAID), and I guess I
> could disable the device-mapper completely in order to access the
> single disks.

Sure, initrd hack.

> 4. But is there a way to enable dmraid, but force no auto detection of
> previous setup?  Even if I choose "Setup as IDE" in compatible mode,
> the previous RAID setup is detected and setup as VIA RAID.

Remove the metadata.

> 
> It seems like a short time since I was unable to use the "FAKE" RAID
> setup of my motherboard, but now I seem to be unable to stop it ;)

Ain't that safe ? ;-)

Regards,
Heinz

> 
> Cheers,
> Martin
> 
> PS! Sorry if this is a noob question in the wrong maling list :)
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