degraded RAID performance after OS upgrade, and drives added.

[Derrick MacPherson]

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" <cswiger at mac.com>
To: "Derrick MacPherson" <dmacpher at vfs.com>
Cc: freebsd-questions at freebsd.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