http://download.intel.com/support/motherboards/server/srcsas18e/sb/axxrpcm2_
tps_10.pdf

Benefits are identified in this PDF.
Data caching (write-back cache can greatly improve write performance)

Busy databases servers commonly need lots of I/O

Also consider running RAID10 if you have drive availability (4 drive
minimum) as you will get much higher I/O performance with that as well
especially with writes. Though if you need the capacity, RAID5 will give you
one drive more of capacity. RAID10 can also give you a smaller chance of
data loss due to drive failures as you can potentially lose up to half of
your drives and still operate whereas using RAID5 and losing 2+ drives =
disaster.


-----Original Message-----
From: tclug-list-bounces at mn-linux.org
[mailto:tclug-list-bounces at mn-linux.org] On Behalf Of Robert De Mars
Sent: Wednesday, May 28, 2008 10:30 AM
To: tclug-list at mn-linux.org
Subject: [tclug-list] OT - Hardware Advice

Hello, and a good day to you all.  I am about to order a new server for my 
job, and I was wondering about the raid controller option. 

The box is going to used for running a very busy database. 

I have the option for
Intel SAS RAID Controller   or 		
Intel SAS RAID Controller w/ Portable Cache Module  (Add $450.00) 

I am planning on running 2 drives as raid 1 for the OS (Slackware), and 3 
drives as raid 5 for the database. 

What is the benefit of the Portable cache module.  I am not concerned about 
the price, just if this is something I should consider. 

Any thought would be great. 

Thank You!!! 

Robert De Mars
http://b-o-b.homelinux.com

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