Re: performance problems with raid10,f2

[Keld Jørn Simonsen <keld@xxxxxxxx>]

On Sat, Mar 15, 2008 at 12:11:51AM +0100, Keld Jørn Simonsen wrote:
> Hi
> 
> I have a 4 drive array with 1 TB Hitachi disks, formatted as raid10,f2
> 
> I had some strange observations:
> 
> 1. while resyncing I could get the raid to give me about 320 MB/s in
> sequential read, which was good. After resync had been done, and with
> all 4 drives active, I only get 115 MB/s.

This was reproducable. I dont know what could be wrong.
I tried to enlarge my readahed, but the system did not allow me to have 
more than a 2 MiB readahed, - well that should be ok for a 4 disk array
with 256 kiB chunks?

I did try to have chunks of 64 kiB - but no luck.

It seemed like it is something that the resync process builds up.
What could it be?

Best regards
keld
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