degraded RAID performance after OS upgrade, and drives added.

That seems like a pretty crazy drop in performance, more
than one would expect. The machine is busy but not busy
enough to warrant this.. Imo.. Is there a way to test to
confirm?

-----Original Message-----
From: "Chuck Swiger" <cswigermac.com>
To: "Derrick MacPherson" <dmacphervfs.com>
Cc: freebsd-questionsfreebsd.org
Sent: 11/30/06 10:39
Subject: Re: degraded RAID performance after OS upgrade, and
drives added.

On Nov 29, 2006, at 6:18 PM, Derrick MacPherson wrote:
> We updated to 6.1 this weekend and added 3 300gb drives
to the  
> external raid cabinet, they were to go on a seprate
controller but  
> the server happens to have a few other boxes on top
making it  
> impossible at that time, so we put the 3x300  (RAID5) ,
upgraded  
> the OS and  performance is very poor. When I run systat
I see  
> upward of 300 tps on the problematic array (da2) and
under systat - 
> vmstat :

It's normal for RAID-5 to perform worse than a single
drive-- and  
sometimes it performs much worse, as in nearly an order of
magnitude  
slower, for the case of very small writes.  If you value
performance,  
choose another RAID level like RAID-0, RAID-1, or RAID-10.

-- 
-Chuck


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