On Mon, 25 Jun 2007, Justin Piszcz wrote:

On Mon, 25 Jun 2007, Bill Davidsen wrote:

quoted

Justin Piszcz wrote:

quoted

I have found a 16MB stripe_cache_size results in optimal performance after 
testing many many values :)

We have discussed this before, my experience has been that after 8 x stripe 
size the performance gains hit diminishing returns, particularly for 
typical write instead of big aligned blocks, possibly with O_DIRECT. I 
would suggest that as a target even on a low memory machine.

Do your tests show similar? I was only able to test three and four drive 
setups using dedicated drives.

-- 
bill davidsen [off-list ref]
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979

I will re-benchmark with my current setup, however:

Each of these are averaged over three runs:

128k_stripe: 69.2MB/s
256k_stripe: 105.3MB/s
512k_stripe: 142.0MB/s
1024k_stripe: 144.6MB/s
2048k_stripe: 208.3MB/s
4096k_stripe: 223.6MB/s
8192k_stripe: 226.0MB/s
16384k_stripe: 215.0MB/s

This was with 6 sata disks.

Justin.
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I set it to 32 and my machine has several hung processes in D state, not 
good.  I will start with 128k and up.

Justin.