[ale] Raid perf?

[Jeff Lightner]

Other than performance is the fact that RAID10 can actually suffer TWO
disk failures before the raid set goes away.   Haven't worked with RAID6
so don't know its redundancy.

-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Greg
Freemyer
Sent: Friday, October 24, 2008 2:52 PM
To: Atlanta Linux Enthusiasts
Subject: Re: [ale] Raid perf?

All,

If anyone cares I found this Dell doc:

http://www.dell.com/downloads/global/products/pvaul/en/PERC6_PerfWP_WMD1
120.pdf

Per it, Raid 6 is in theory 3 times less efficient than Raid 10 on
writes.

So to maintain the same write performance as my 4-disk Raid 10 I would
need a 12-disk Raid 6.

That is worse than I realized, but feasible for my needs.  (I think
250GB drives are down to $60 or so.  Thus 12 is only $700.  Obviously
I need the controller card too.  Haven't priced that yet.  I do have
big chassis that can hold the drives.)

Time for me to do a better job of characterizing my app to see what
percentage the i/o's are reads vs. writes.

Greg

On Fri, Oct 24, 2008 at 9:53 AM, Greg Freemyer <greg.freemyer at gmail.com>
wrote:
> All,
>
> I have a Raid 10 (4x500GB) under Fedora using software raid that I
> want to replace with a Raid 6 (6x1TB).
>
> Does anyone know a website that will help me understand what the
> impact will be from a write perspective?  Assuming random DB style
> writes, not sequential.
>
> I'm curious about both theoretical and real world  (3ware or linux
> software raid) performance numbers.
>
> Thanks
> Greg
> --
> Greg Freemyer
> Litigation Triage Solutions Specialist
> http://www.linkedin.com/in/gregfreemyer
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>
> The Norcross Group
> The Intersection of Evidence & Technology
> http://www.norcrossgroup.com
>



-- 
Greg Freemyer
Litigation Triage Solutions Specialist
http://www.linkedin.com/in/gregfreemyer
First 99 Days Litigation White Paper -
http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pd
f

The Norcross Group
The Intersection of Evidence & Technology
http://www.norcrossgroup.com
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