Date: Tue, 05 Sep 2000 23:19:49 GMT From: "Terje Oseberg" <oseberg@hotmail.com> To: joe@archive.org Cc: freebsd-questions@FreeBSD.ORG Subject: Re: FreeBSD and IDE RAID (Abit kt7-raid) Message-ID: <F104v0YKpDS7hx27kBn00003751@hotmail.com>
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It is my understanding (although I'm not sure) that FreeBSD bypasses
the BIOS when accessing the drive.
I once tried a BIOS RAID back when MR-BIOS existed and Win 95. I was
able to get Win 95 to work with it temporarily, but the 32 bit IDE
drivers also bypass the BIOS and therefor the RAID didn't work with
the 32 bit drivers. It turned out that there was more overhead in
running the 16 bit BIOS drivers + the BIOS RAID than just using the
32 bit drivers alone. (The ability to do write back caching in the
OS was lost)
From the looks of this Abit M/B, it appears that this is a hardware
RAID. There are actually 4 IDE connectors on this M/B.
Apparently to the BIOS even any drives set up as RAID will appear
as one single drive.
A friend of mine just bought this M/B, so I'll probably get a chance
to take a look at it soon, but I was interested in what the FreeBSD
group thought about it before I started to mess with it and run a
few benchmarks.
My friend will be installing Linux on his M/B, but I'm sure he
won't have any problems with me spending a few hours at his house
installing FreeBSD on a pair of drives to see what happens.
Terje
PS. Thanks for that site. It's been a while since I have looked at
RAID and I had forgotten what all the levels were and what numbers
matched with what. That site is clear, simple and to the point.
>I'll apologize for my minimal input other than saying that running from an
>onboard RAID will \not\ be 'faster'. in fact, most RAID will be slower.
>you can get a good RAID overview from
>http://www.discovery-uk.com/RAID/rg_sect1.htm among many other places. one
>thing to know is that FreeBSD has somewhat built-in RAID support (CCD, man
>ccd & man ccdconfig(depending on version)) which would give you more
>control over your hardware. filesystem layout is very important.
>
>if the RAID is in the BIOS, the OS (which ever you use) should run just
>fine. can't really get much info from the abit site though.
>
>hope this helps.
>
>joe
>
>
>On Tue, 5 Sep 2000, Terje Oseberg wrote:
>
> > Hi,
> >
> > I'm wondering about the new KT7 motherboard from Abit and
> > the RAID which it supports.
> >
> > http://www.abit.com.tw/english/product/motherboards/kt7-raid.htm
> >
> > What I'm wondering is, would anyone believe that FreeBSD would
> > be able to boot from and access a RAID of this type as if it
> > were a normal drive?
> >
> > I don't know anything about this motherboard yet other than
> > what I've been able to find online. My hope is that they actually
> > make the drives physically look like a single faster IDE drive
> > such that FreeBSD would see it as such and work as normal except
> > twice as fast.
> >
> > What do ya'll think?
> >
> > Terje Oseberg
> >
> >
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