[Gllug] Hardware RAID On-Disc Format

[Daniel P. Berrange]

On Mon, Mar 15, 2004 at 12:44:06PM +0000, Doug Winter wrote:
> I've been using 3ware IDE RAID cards for a while now, and I've found
> them to be most excellent.  I've basically stopped using software RAID
> and instead shelling out for these 3ware cards.
> 
> I mentioned this to a friend who said he'd never use hardware raid if he
> could avoid it, because of difficulty he had in recovering once.  He
> said that he'd had a (can't remember the brand) raid card blow up on
> him, and then discovered that the individual discs wouldn't work on
> normal IDE controllers and that the on-disc data format was completely
> to cock and basically unrecoverable.

Not only is the data written in a format specific to each card, vendors
have been known to change the format across firmware versions, leaving
you fubar if the controller dies & you have to purchase a new one. Next
up most IDE RAID controllers are merely using a simple microprocessor 
running software RAID. You can bet the performance of these microproc's
doesn't increase at the same rate as the performance of your main CPU,
so there is little chance they'd out perform OS level software RAID for
very long after release, if at all. All in all, I'd never go near an IDE
RAID card & certainly don't assume hardware cards are more reliable or
faster.

Dan.
-- 
|=-               http://www.berrange.com/~dan/gpgkey.txt             -=|
|=-   berrange at redhat.com  -  Daniel Berrange  -  dan at berrange.com    -=|
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