Date: Tue, 10 Apr 2007 14:40:28 -1000 From: Antony Mawer <fbsd-questions@mawer.org> To: freebsd-questions@freebsd.org Subject: Re: Hardware Raid on Intel DG965OT Motherboard Message-ID: <461C2E7C.3040506@mawer.org> In-Reply-To: <20070405115222.GA6399@upful.org> References: <461200AE.4010100@careytech.com.au> <20070404113009.GA93829@upful.org> <46142C3C.8070701@mawer.org> <20070405115222.GA6399@upful.org>
next in thread | previous in thread | raw e-mail | index | archive | help
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
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?461C2E7C.3040506>