Re: raid10 far layout outperforms offset at writing? (was: Help with chunksize on raid10 -p o3 array)

["Keld Jørn Simonsen" <keld@dkuug.dk>]

On Wed, Dec 17, 2008 at 01:50:24PM +0100, Peter Rabbitson wrote:
> Keld Jørn Simonsen wrote:
> > I found this old message:
> > 
> >> Peter Rabbitson
> >> Mon, 19 Mar 2007 06:14:38 -0800
> >>
> > 
> > The links were not valid anymore. I wanted to see the results and 
> > possibly include the results in the performance wiki page
> > I would appreciate some new links here.
> 
> I apologize, I don't have the data available anymore.
'
OK.

> > Furthermore some comments to the post: My take on o3 vs f3 is that both
> > in theory and practice f3 should be much faster for sequential reading,
> > as the layout is equivalent to raid0. For random reading and sequential
> > and random writing f3 and o3 (and the same goes for the more normal f2
> > vs o2) should be about the same, especially when a filesystem and
> > its associated elevator algorithm is employed.
> 
> Yes, this is what I also concluded since I wrote this email. I am in the
> process of upgrading my raid setup, and while I am at it I am leaving
> 5GB blank partitions at the start of all my workstations spindles, so I
> can get some real testing at night. I will share my methodology with the
> list before I commence testing (which should take about 20 days the way
> I am planing it).

I have tried to persuade Neil to change the description for MD to
reflect the above, but until now with no luck.

I look forward to see your new tests!

> But first comes the vacation - happy holidays to you too guys.

Yes, happy holidays to all!

Best regards
Keld
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