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Re: XFS tune to adaptec ASR71605

To: Emmanuel Florac <eflorac@xxxxxxxxxxxxxx>
Subject: Re: XFS tune to adaptec ASR71605
From: Steve Brooks <steveb@xxxxxxxxxxxxxxxx>
Date: Tue, 6 May 2014 15:40:37 +0100 (BST)
Cc: xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <20140506155149.5cf056b5@xxxxxxxxxxxxxxxxxxxx>
References: <alpine.LRH.2.02.1405061104580.24742@xxxxxxxxxxxxxxxxxxxxxx> <20140506130008.13a1a7ee@xxxxxxxxxxxxxxxxxxxx> <alpine.LRH.2.02.1405061408480.24742@xxxxxxxxxxxxxxxxxxxxxx> <20140506155149.5cf056b5@xxxxxxxxxxxxxxxxxxxx>
User-agent: Alpine 2.02 (LRH 1266 2009-07-14)

Yup, they're... weird :) Write speed is abysmal, but random seeks very
high. Please try my settings so that we can compare the numbers more

bonnie++ -f -d ./ -n 50

If you translate the output from my test file with bon_csv2

Did you turn off write cache? did you tune the IO scheduler, read
ahead, and queue length? Here are the settings I'm generally using
with this type of controllers (for better sequential IO):

echo none > /sys/block/sda/queue/scheduler
echo 1024 > /sys/block/sda/queue/nr_requests
echo 65536 > /sys/block/sda/queue/read_ahead_kb

You can check the cache status in the output from

arcconf getconfig 1

If you didn't install arcconf, you definitely should :) If you turned
off the write cache, be aware that this is not the expected mode of
operation for modern RAID controllers... Go buy a ZMM if necessary.


Yes the write speed is very poor.. I am running "bonnie++" again with your params but no sure how long it will take.

 bonnie++ -f -d ./ -n 50

Will thisno be different for our two machines as it seems to generate other params depending on the size of the RAM. All ours have 64G RAM.

I disabled write cache on the controller as there is no ZMM flash backup module and it seems to be advised that way. I could enable it and try another test to see if that is a contribution to the poor write performance. I do have "arcconf" on all our adaptec raid machines.

I have not tuned the IO scheduler, read ahead, and queue length? I guess I can try this.

echo none > /sys/block/sda/queue/scheduler
echo 1024 > /sys/block/sda/queue/nr_requests
echo 65536 > /sys/block/sda/queue/read_ahead_kb

Will this need to be done after every reboot? I guess it could go in "/etc/rc.local" ?

Thanks, Steve

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