vinum performance

[Chuck Swiger]

Lukas Ertl wrote:
[ ... ]
> I created several RAID 0 and RAID 5 volumes with different stripe sizes
> and let bonnie++ run over the filesystems. I was quite disappointed about
> the RAID 5 performance, and even the RAID 0 performance wasn't too good
> (a plain single disk filesystem was almost as fast as or even faster than
> a RAID 0 stripe, and I wouldn't expect that).
> 
> RAID 5 performance was really a mess, some of the test took more than
> 30min. to complete.

There are three goals or priorities to choose from when configuring 
RAID: performance, reliability, and cost.  What are yours?

Also, what tasks you intend to use the RAID filesystem for are critical 
to consider, even if the answer is simply "undifferentiated 
general-purpose storage".  In particular, RAID-5 write performance is 
going to be slow, even with RAID hardware support which offloads the 
parity calculations from the system CPU(s).  RAID-5 is best suited for 
read-mostly or read-only volumes, where you value cost more than 
performance.

Um, that is a dual-channel card, and you're splitting drives onto both 
channels, right?  Anyway, if I had your hardware and no specs as to what 
to do, I'd probably configure 2 disks as a RAID-1 mirror for an OS boot 
volume; configure 4 disks as RAID-10; and use the 7th disk as a staging 
area, hot spare, etc.

-- 
-Chuck