[conspire] Re: Dell and big disks

Rick Moen rick at linuxmafia.com
Sat Nov 6 19:42:46 PST 2004

Quoting Adrien Lamothe (a_lamothe at yahoo.com):

> I built and configured a dual-boot Linux/Windows 2000 box with a SCSI
> RAID that I striped and it doesn't have any problems. It boots into
> either OS. The RAID card is an Adaptec (think it was a 2010S, but
> don't remember now, it lives at a client site, Lawrence Berkeley Labs,
> I can find out the model if anyone is interested.)

That sounds like a real RAID card.  To my knowledge, all Adaptec RAID
controllers except the 1200 series (which use a Silicon Image chip, not
an Adaptec one) are real RAID.  That means that the OS and its drivers
don't see, and don't have to manage, individual disks, but instead see 
RAID volumes (which you typically establish separately using either the
RAID BIOS program or a manufacturer-furnished utility).

"RAID" chips built into motherboards are inevitably, on grounds of
minimising expense, what on comp.os.linux.hardware are termed "fakeraid"
controllers.  I like that term so much that I've adopted it in my page
on Serial ATA considerations for Linux:

"Serial ATA" on http://linuxmafia.com/kb/Hardware/

> Perhaps the RAID controller on the computer in
> question can't boot when striped? Its worth trying.

1.  I'm pretty sure we're talking about mirroring (RAID1) not striping

2.  The fact that a motherboard-embedded chipset purports to do its own
RAID (and, inevitably, turns out to be fakeraid) doesn't mean you need
to use that functionality.  Which is a good thing, since fakeraid
implementations inevitably suck compared to the same functionality in
Linux software RAID (the "md" = multiple device driver).

3.  I vaguely recall that booting from a Linux software-RAID mirrored
volume is tricky, in some fashion or other.  When in doubt on such
matters, start at your favourite mirror of the Linux Documentation
Project and browse the HOWTOs.  (If you don't have a favourite, go to 
http://www.tldp.org/ .)  Notice the mnemonic:  The Linux Documentation
Project, tldp.org .  And, if you can't remember that, you can always 
google for "Linux Documentation".

Soon, you find yourself in the alphabetical list of all HOWTOs:

And that leads you, in this case, to the Software-RAID-HOWTO .
It has a section about issues involved with "Booting on RAID" (section 7.3) 
and similar matters.

Cheers,                 There are 10 kinds of people in the world, those who 
Rick Moen               know ternary, those who don't, and those who are now 
rick at linuxmafia.com     looking for their dictionaries.  -- Ron Fabre

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