[CentOS-virt] Slightly OT: FakeRaid or Software Raid

Ben M. centos at rivint.com
Wed Dec 2 22:44:33 UTC 2009

Thanks for sharing Grant. Your point about hardware raid is well taken. 
However, the discussion is about Fake-Raid vs. Software RAID1 and 
controller/chipset dependence and portability. The portability of a 
software RAID1 hard drive to an entirely different box is, I have 
learned, much higher and less time consuming.

Grant McWilliams wrote:

> He had a two drive RAID 1 drives and at least one of them failed but he 
> didn't have any notification software set up to let him know that it had 
> failed. And since that's the case he didn't know if both drives had 
> failed or not. I wonder why he things software RAID would be a) more 
> reliable b) fix itself magically without telling him.  He never did say 
> if he was able to use the second disk. I have 75 machines with 3ware 
> controllers and on the very rare occasion that a controller fails you 
> plug in another one and boot up.
> I don't use software RAID in any sort of production environment unless 
> it's RAID 0 and I don't care about the data at all. I've also tested the 
> speed between Hardware and Software RAID 5 and no matter how many CPUs 
> you throw at it the hardware will win.  Even in the case when a 3ware 
> RAID controller only has one drive plugged in it will beat a single 
> drive plugged into the motherboard if applications are requesting 
> dissimilar data. One stream from an MD0 RAID 0 will be as fast as one 
> stream from a Hardware RAID 0. Multiple streams of dissimilar data will 
> be much faster on the Hardware RAID controller due to controller caching.
> Grant McWilliams
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