Thread (24 messages) 24 messages, 5 authors, 2007-06-26

Re: stripe_cache_size and performance [BUG with =64kb]

From: Justin Piszcz <hidden>
Date: 2007-06-25 19:49:01


On Mon, 25 Jun 2007, Justin Piszcz wrote:

On Mon, 25 Jun 2007, Justin Piszcz wrote:
quoted

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

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Running test with 10 RAPTOR 150 hard drives, expect it to take awhile until 
I get the results, avg them etc. :)

128k,256k,512k,1024k,2048k,4096k,8192k,16384k

Justin.
Definitely a kernel bug, I set it to 64kb and it stayed in D-state until I 
ran alt-sysrq-b.

Pretty nasty!

Justin.
Ack, help??

[   64.032895] Starting XFS recovery on filesystem: md3 (logdev: internal)
[   66.210602] XFS: xlog_recover_process_data: bad clientid
[   66.210656] XFS: log mount/recovery failed: error 5
[   66.210709] XFS: log mount failed

After I ran 64kb it killed my RAID!
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