specs for running 35 machines

[Gavin McCullagh]

Hi,

On Wed, 15 Aug 2007, Jim Kronebusch wrote:

> > RAID 5 is not the most fault tolerant -- although it is better than RAID0
> > or no RAID at all.
> > 	http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt
> 
> What was in my head didn't completely make it to the screen, I was
> thinking RAID5 is the most fault tolerant for the money, not out of all
> options.  I personally chose RAID10 (RAID 1+0) but many cheaper RAID
> controllers don't handle that and RAID10 sacrifices a good share of drive
> space, where RAID5 looses less.

Fair enough, though the article does conclude:

  "Conclusion?  For safety and performance favor RAID10 first, RAID3 second,
   RAID4 third, and RAID5 last!"

RAID5 is really the most disk-space efficient.

Another debate is whether to use software or hardware RAID.  Linux's
software RAID is very capable, although it comes at some CPU and PCI
bandwidth cost.  On the other hand, you remove a lot of worries like:

 - replacing controllers that die
 - proprietary driver/firmware/kernel compatibilities
 - proprietary user space tools for array status/problem reporting
 - sourcing the right disk to replace failed ones
 - you can have any of the above RAID configs 

Having been through some bad times with hardware RAID controllers, I
personally tend to favour linux MD now.

Gavin