[Wylug-help] Can't install on Hardware SATA RAID10 on startech.com PCISATA4R1

[John Hodrien]

On Wed, 29 Feb 2012, Chris Davies MBCS wrote:

> On 29/02/12 09:34, Gary Stainburn wrote:
>> However, I cannot install Fedora. I've tried 14 and 16.  Both installs see the
>> hardware RAID
>
>> but when I select it and try install the system crashes.
>
> Is there an option for "just use the disk", instead of Fedora trying to
> be clever about recognising that it's found BIOS level hardware RAID?
>
> I've installed Debian on a fair number of Dell servers, all of which
> (bar a couple) have had hardware RAID. The resulting virtualised disk(s)
> have been seen by the kernel and presented simply as /dev/sda, /dev/sdb,
> etc. Additional tools from Dell allow monitoring of the slices within
> the RAID array, but to the remainder of the OS each is just "a (big) disk".

That's what you see if it's true hardware RAID (in Dell speak, all their PERC
Hxxx line are hardware RAID, the PERC Sxxx aren't).  With fakeraid there's
merely a standard for metadata that the OS picks up on, but it can also see
the disks as disks.

This has the *wonderful* sideeffect of it being possible to accidentally mount
half of a RAID 1 set, then reboot and mount it as whole again, with the two
sides now being different, and neither the OS nor the RAID card notice.  Joy
of joys.

This is much easier than you think.  In your initrd, there's often something
along the lines of this:

Activate RAID array
Mount LABEL=/
Resume boot

What *can* happen is that the actual activation fails, but is ignored (on
CentOS 5 this was ignored by default).  Then it looks for a partition with
LABEL=/ which it finds (actually it finds two) and mounts and blunders on.
Ace.

jh