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 any
>> production server. Get a real raid controller, or use gmirror if you
>> plan to mirror. I use several of these board sin production with gmirror.
> Why do you recommend against on-board RAID controllers?
Think about what happens if one of your disks dies. Sure, the machine will
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 the
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 interface
with the card from the OS level, and it will have some mechanism for alerting
the admin to problems.
Cheers,
Matthew
--
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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