hardware mirrors recognized as individual disks in fbsd

[Damian Wiest]

On Tue, Jan 16, 2007 at 11:33:47AM -0700, Steve Franks wrote:
> I'm tired of win2k crashing, and we won't even go into my opinion of vista's
> strongarm marketing tactics (read: changing my hardware means I have to pay
> again? they can keep their OS).
> 
> Problem is, I've got 320GB of accumulated detrius on ntfs volumes to
> migrate.  I see there is some good r/w ports for ntfs, so I'm willing to
> evaluate that to see if it's stable (shoestring budget here obviously - this
> is my personal stuff only).
> 
> Forging ahead, I get ready to start playing the mounting game, but
> lo-and-behold, suddenly I have 4 disks whereas in windows I had two.  Now I
> praise FreeBSD for it's superior intellect here, but now I have a problem.
> I want two 160GB mirrored volumes, not 4 unmirrored ones.  The RAID is an
> ASUS P5DR1-VM motherboard with a ULI raid chipset onboard.  Very nice setup
> for the money.
> 
> Is this normal?  Am I going to break my mirror if I mount a single disk?  If
> so, how do I mount a mirror?
> 
> Thanks,
> Steve
> 
> -- 
> Steve Franks, KE7BTE
> Staff Engineer
> La Palma Devices, LLC
> http://www.lapalmadevices.com
> (520) 312-0089

It sounds like your onboard RAID chip is either not supported, or the 
appropriate driver is not being loaded.  Can you post the output of 
dmesg?

Also, be aware that you may not really have a hardware RAID chip.  
Many (most?) times the onboard chips simply make multiple disks look 
like a single LUN to the operating system; they also require driver 
support.  Real hardware RAID chips/cards tend to be expensive, 
proprietary, don't require an OS driver and include a battery backup
system for data in the RAID cache should the system lose power.

You may want to read up on gmirror.

-Damian

ps. I've got at least a half-dozen different x86 system boards that
    include these crappy RAID chips from vendors like nVidia, Intel, 
    Adaptec, LSI, etc.  Typically you get closed-source, Windows-only
    driver support.

pps. If you do want real hardware RAID support under FreeBSD, I've had
     great experiences with the Promise arrays (m500 and m300) and
     one of the PCI cards (I'd have to check on the exact model).