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1703
August 16th, 2007 18:00
IOSTAT, Linux and pseudo devices
K, so, I'm seeing very odd results with IOSTAT when looking at /dev/emcpower(x) including 100% utilization when I have confirmed there is zero I/O being generated. I remember reading this was an issue before but can't seem to find anything definetive. It would be nice if there was something clearly stating what the issue is if there is one and, more importantly, how to work around it
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Navin-Swn_9
66 Posts
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August 17th, 2007 01:00
If you want to check the utilization on a EMC device. you can use "powermt display dev=emcpower(x) every=n". (where n=numer of seconds).The Q/IOs column will show you if there are any I/O waiting in the Que. (suggesting that the device is highly utilized).
Navin.
Conor
341 Posts
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August 17th, 2007 02:00
Extract:
- Iostat does not work on emcpower devices.
- Kernel does not pass the information needed to iostat.
- This is documented in the PowerPath 4.3 Release Notes. A partial fix is included in PowerPath 4.3.5 and the Release Notes have been updated to note the problem.
From the 4.3 release notes:
Bug 235653
Running I/Os on pseudo or native devices will result in incorrect values for the iostat extended attributes viz %util and avgqu-sz for that pseudo or native device and its partitions even after the I/Os are stopped.
Navin-Swn_9
66 Posts
0
August 17th, 2007 03:00
I guess i misunderstood his question. This is KB is bang on the question
Navin
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