Nice looking 'disk array'

[Dave Bour]

I was a user of Adaptec 2410 cards...note the past tense.  It's supposedly a true hardware raid contoller.  Problems were, I'd get a failure on at least one of them (2 on board) at least every 3 months.  1/2 the time, it meant the loss of the array.  I finally gave up and switched to dumb promise cards...on soft raid.

The problems included complete lack of support from Adaptec, overheating issues, slow rebuilds (1.5tb array took about 1 week to complete), and incompatibility between different firmwares on the cards, meaning I couldn't even card swap in case of a failure.  

So now, it's soft raid for me.  Crazy part, in light of this thread, is that swap (to soft raid) happened about 2 months ago with my first soft raid failure this weekend.  I got an email that it happened.   It brought the spare drive into play and in 3 hours, was finished the rebuild.  I shut the box down this morning, swapped out a drive and brought it back up, new spare drive online in 10min after that.  Single boot.  I could never do it that easy on the hardware raid cards.

I'm sold on soft raid now.  And I'm not locked into anyone's propriety firmware, formats, etc.  And I can easily expand beyond the 4 + 1 hot spare now too, which may be happening soon too.  My only wish is that I'd done raid 6 instead of 5 reducing the risk of a controller failure, but maybe that's a project for this summer...

My $0.02.
Dave



-----Original Message-----
From: owner-tlug-lxSQFCZeNF4 at public.gmane.org [mailto:owner-tlug-lxSQFCZeNF4 at public.gmane.org] On Behalf Of Madison Kelly
Sent: Monday, January 29, 2007 2:05 PM
To: tlug-lxSQFCZeNF4 at public.gmane.org
Subject: Re: [TLUG]: Nice looking 'disk array'

Byron Sonne wrote:
> IMO, hardware raid is a better performer and more reliable. When it's 
> hardware that's where the real advantages come in.

I feel that depends on the controller and hardware. I've seen so many "hardware" RAID controllers, which in reality are little more than the equivalent of winmodems, fail. Then unless you have a spare controller, you are SOL. In the cases where the alternative is low-end RAID hardware like that, I always recommend using software arrays. At least then the array is not tied to the hardware.

Now, if you get a controller with a dedicated processor then you are in business. Generally those controllers have (at least) a dedicated MIPS CPU for handling XOR calculations (specially important in a failed
state) with it's own dedicated RAM for caching and often even have their own battery backup on-board to maintain unwritten data in case of a power failure. On DB systems, this is specially important.

http://www.adaptec.com/en-US/products/sas_cards/performance/SAS-4800/

Look like it's inline with what I am talking about (though I couldn't see specs on it's proc, but it's priced in the range to have one).

My $0.02 :)

Madi
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