On 5/04/2007 1:52 AM, Alexander Anderson wrote:
Thu, Apr 05, 2007 at 08:52:44 AM, Antony Mawer wrote:
I have Intel D975XBX2 with two on-board SATA RAID controllers: one is Intel
Matrix and the other is Marvell storage. I have FreeBSD 6.2 with RAID-5
using Intel Matrix Storage. It seems to work fine.
You may want to re-think that option... according to the ataraid(4) man
page, RAID5 is not functional (ie. you have about as much data safety as
a RAID0 stripe set does):
CAVEATS
RAID5 is not supported at this time. Code exists, but it neither uses
nor maintains parity information.
The ataraid driver provides *software* RAID. But doesn't Intel Matrix
Storage gives *hardware* RAID support? How could I tell if software is at
play?
I'm fairly certain that all ar# devices (ar0, etc) are ataraid-powered,
and thus are software RAID. If it is a hardware RAID device, typically
the RAID controller presents a single drive (or one drive for each RAID
volume) to the OS, and the OS can be ignorant of the number of
underlying drives.
Also, from man ataraid:
The ataraid driver can read the following metadata formats:
...
o Intel MatrixRAID
Which suggests that is is, indeed, just a software RAID setup. That is,
the BIOS-based bit just writes configuration metadata to the drives, and
its up to drivers at the OS level to perform the actual RAID
operations using that data.
--Antony
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