1 processor vs. 2

[Charles Swiger]

On Mar 3, 2004, at 4:26 PM, Stefan Cars wrote:
> Okey, but if you would compare RAID-1 on two disks compared to RAID-5 
> on
> three disks then ? What would be the faster ?

RAID-1 will be about 50% faster than RAID-5 doing reads regardless of 
size, and will also be *much* faster doing small writes-- by a factor 
of 4, perhaps.

[ There is a potential optimization for RAID-5 using very large 
writes-- ie, bigger than the RAID interleave size * (# of disks - 1)-- 
that might make it more comparable with RAID-1's performance, only I 
believe FreeBSD breaks up large I/O requests into 32K or so, thus there 
generally never is the potential to not read the data before writing. ]

-- 
-Chuck