HP Embedded SATA RAID controller (FreeBSD 6.2)

[Ted Mittelstaedt]

----- Original Message ----- 
From: "George Vanev" <vanev at unisoft-ltd.com>
To: "Ted Mittelstaedt" <tedm at toybox.placo.com>
Cc: "FreeBSD Questions" <freebsd-questions at freebsd.org>
Sent: Thursday, January 25, 2007 1:33 AM
Subject: Re: HP Embedded SATA RAID controller (FreeBSD 6.2)


>
> ----- Original Message ----- 
> From: "Ted Mittelstaedt" <tedm at toybox.placo.com>
> To: "George Vanev" <vanev at unisoft-ltd.com>; "FreeBSD Questions"
> <freebsd-questions at freebsd.org>
> Sent: Thursday, January 25, 2007 10:57 AM
> Subject: Re: HP Embedded SATA RAID controller (FreeBSD 6.2)
>
>
> >
> > Hi George!
> >
> > Common problem.  The issue isn't that the FreeBSD driver cannot talk
> > to the SATA controller.  It can do that just fine.
> >
> > The problem is that HP is using a modified metadata format on the
> > disk drives.
> >
> > What you need to do is go into the Proliant BIOS and DISABLE
> > the SATA raid.  This of course means any raid arrays, mirrored or
> > otherwise, that you have created, cannot be used from BIOS.  Just
> > leave the BIOS settings so that the SATA controller is enabled, but
> > the RAID on the SATA controller isn't.
> >
> > Then boot FreeBSD 6.2.  It will see 2 disk drives.  (or more or however
> > many you got)
> >
> > Now, if you want a raid mirror here is what you do.  Load a scratch
> > install of FreeBSD 6.2 on the first disk.  Run atacontrol to create a
> > mirror on both disks.  This writes out a metadata format that FreeBSD's
> > disk driver understands.  This will trash your freebsd install of
course.
> > No problem.  Reboot from the installation CD and now you will see
> > the 2 disks, plus ar0 (the mirror)   Install to that and your all set.
> >
> > Basically the only difference between doing it HP's way by creating
> > the RAID from HP BIOS and doing it the FreeBSD way is that
> > the HP BIOS is unaware of the FreeBSD metadata format so you
> > cannot see or rebuild an array from BIOS that was created in
> > FreeBSD, and FreeBSD is unaware
> > of HP's metadata format so you cannot see or rebuild an array
> > from FreeBSD that was created in BIOS
> >
> > As far as how the actual raid mirror works, it's exactly the same.
> > In fact, better, since you can rebuild a FreeBSD array from
> > FreeBSD and it's about 10 times faster than rebuilding it from
> > HP's BIOS.
> >
> > Ted
> >
> > ----- Original Message ----- 
> > From: "George Vanev" <vanev at unisoft-ltd.com>
> > To: "FreeBSD Questions" <freebsd-questions at freebsd.org>
> > Sent: Wednesday, January 24, 2007 4:35 AM
> > Subject: HP Embedded SATA RAID controller (FreeBSD 6.2)
> >
> >
> >> I have HP ProLiantML 110 G3 server.
> >> I am trying to install FreeBSD 6.2.
> >> But it doesn't seem to recognise the RAID controller.
> >> I don't know what exactly is the controller.
> >> In the hp site I didn't find anything usefull,
> >> except that this is "HP embedded SATA RAID controller"
> >> Not much, uh?!
> >>
> >> Any one could help?!
> >> Regards
> >> --
> >> George Vanev
> >>
> >> _______________________________________________
> >> freebsd-questions at freebsd.org mailing list
> >> http://lists.freebsd.org/mailman/listinfo/freebsd-questions
> >> To unsubscribe, send any mail to
> > "freebsd-questions-unsubscribe at freebsd.org"
> >>
> >
> >
> >
>
> Just great!!!
> Thanks a lot!!!
>
> But still it will use the hardware RAID controller, right?!
> It is not a software RAID, I hope.
>
>

I hate to disappoint you but the embedded SATA controller chip is
a software raid chip, whether you set it up with BIOS or with FreeBSD's
drivers.  Not that this matters, however.  Mirroring does not do parity
calculation and so there is no need for a hardware controller.  All the
SATA chip does when the driver sees a mirror is it sets a flag in the
SATA chip that tells the chip to duplicate any writes to both disks. Reads
always happen from the primary disk.

For true SATA hardware raid you need a card like a 3ware or highpoint
card, these can do raid 5, etc.

Ted