[AccessD] Storage Advisors > Blog Archive > Yet another RAID-10 vs RAID-5 question

Having a high end controller definitely helps!

I've been using RAID configs on my work desktops for about 10 years.
But since they were desktops, I only used OS based or onboard RAID
controller.  The server RAID controllers are much more powerful though
it's harder to do a performance test between a desktop and a
server...LOL.

Drew

-----Original Message-----
From: accessd-bounces at databaseadvisors.com
[mailto:accessd-bounces at databaseadvisors.com] On Behalf Of jwcolby
Sent: Friday, June 25, 2010 8:00 AM
To: Access Developers discussion and problem solving
Subject: Re: [AccessD] Storage Advisors > Blog Archive > Yet another
RAID-10 vs RAID-5 question

Most people are in agreement that reads are virtually full speed, or at
least there are no parity 
calcs going on.  The whole point really is that to really get any speeds
out of raid, a hardware 
controller helps immensely.  I decided to bite the bullet and spend the
bucks for the Areca line, 
even though they are more expensive than the competition, and I have not
been disappointed.

The smaller controllers (up to 8 drive) have a fixed 256 megs of cache,
soldered right on the board. 
  I have one of those, my first purchase.  I later purchased an "open
box" 16 drive controller and 
it has a dimm socket, which I populated with the maximum 2 gigs of ram.

In any case, you are at the mercy of the manufacturer as to
implementation.  In most cases software 
raid, using the motherboard chipset and software run by the operating
system, are VERY slow on 
writes, though the reads are pretty good.  Where the hardware
co-processors can help is turning the 
raid into an orchestra.  These guys come to know RAID and how to do it
right.  I chose Areca based 
on reviews in the magazines that consistently placed them way above the
competition.  I don't have 
the links any more but the numbers were not just a small percentage
faster.

Anyway, back when I was trying to figure out how to do this I read the
reviews and made a decision 
based on the numbers that Raid6, at least as implemented by Areca, was a
valid storage option.

John W. Colby
www.ColbyConsulting.com


Drew Wutka wrote:
> Great article, thanks for the link John.  There is one issue with the
> technical details.  The 'reading' is on paper like that, but most real
> life RAID 5's are slower on read then the same drives in a raid 0,10
or
> 0+1.  (Probably due to the overhead of the parity being
checked...would
> depend on the operation of the actual controller.)
> 
> Drew
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