Date: Sat, 15 Jul 2006 07:29:37 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Javier Henderson <Javier@KJSL.COM> Cc: Mike Jakubik <mikej@rogers.com>, freebsd-stable@freebsd.org Subject: Re: Intel ICH7R RAID controller working on 6.1/STABLE? Message-ID: <44B88B51.10607@infracaninophile.co.uk> In-Reply-To: <20060715011112.GB32358@skyhawk.kjsl.com> References: <20060714165735.L15214@bunning.skiltech.com> <44B8094C.3040007@rogers.com> <20060715011112.GB32358@skyhawk.kjsl.com>
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Javier Henderson wrote:
> * Mike Jakubik <mikej@rogers.com> [060714 17:15]:
>> The chipset is supported, but i wouldn't recommend onboard raid for an=
y=20
>> production server. Get a real raid controller, or use gmirror if you=20
>> plan to mirror. I use several of these board sin production with gmirr=
or.
=20
> Why do you recommend against on-board RAID controllers?
Think about what happens if one of your disks dies. Sure, the machine wi=
ll
carry on running. With an on-board controller there are two problems:
i) How do you get notified that a disk has died
ii) How do you replace the drive
(i) you'ld likely only find out about at reboot time, or by noticing a
change in the pattern of blinken-lights on the machine. (Don't laugh --
it happens)
(ii) is not just about having to power off the machine and swap out the
hardware: it's not uncommon for on-board RAID-1 setups to be unable to
rebuild a mirror by duplicating the good disk onto the replacement one. =
That
means blowing everything away and recovering from backup. By which time
you've had so much downtime that you might as well not have bothered with=
RAID in the first place.
The advantage of a good RAID controller -- like one of the 3ware cards
-- or of gmirror is that combined with hot-swap disk (and pretty much all=
SATA drives nowadays have hot-swap capability; you just need to find a
chassis with the right sort of drive bays) then you can take out the dead=
disk, replace it with a good one and rebuild the array *without taking th=
e
machine down*.
gmirror will alert you to failures in the nightly e-mail if you enable
the 406.status-gmirror periodic script. Similarly a good hardware RAID
controller will have a system level control application to let you interf=
ace
with the card from the OS level, and it will have some mechanism for aler=
ting
the admin to problems.
Cheers,
Matthew
--=20
Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard
Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
Kent, CT11 9PW
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