Re: [ADMIN] H/W RAID 5 on slower disks versus no raid on

On Thu, 21 Nov 2002, Bjoern Metzdorf wrote:

> > In fact, the linux kernel supports >2 drives in a mirror.  Useful for a 
> > mostly read database that needs to handle lots of concurrent users.
> 
> Good to know.
> 
> What do you think is faster: 3 drives in raid 1 or 3 drives in raid 5?

Generally RAID 5.  RAID 1 is only faster if you are doing a lot of 
parellel reads.  I.e. you have something like 10 agents reading at the 
same time.  RAID 5 also works better under parallel load than a single 
drive.

The fastest of course, is multidrive RAID0.  But there's no redundancy.

Oddly, my testing doesn't show any appreciable performance increase in 
linux by layering RAID5 or 1 over RAID0 or vice versa, something that 
is usually faster under most setups.