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cletus
Asked: 2009-05-02 16:51:00 +0800 CST

How to identify I/O bottlenecks on a Linux server?

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How do you determine that the performance of your Linux server is I/O bound and, perhaps more importantly, what process or processes are casuing the problem?

performance linux io tuning

5 Answers

  1. I wrote a comprehensive guide to tracking down performance bottlenecks on Linux systems for work: http://web.archive.org/web/20101028025942/https://anchor.com.au/hosting/development/HuntingThePerformanceWumpus . Covers more than you asked for, but it'll (hopefully) help you track down the problem you're seeing regardless of the actual source.

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  2. Top has a field called "iowait". If your system is seeing a lot of that, you know something's up. There's also iotop!

    Package: iotop:
Description: simple top-like I/O monitor
 iotop does for I/O usage what top(1) does for CPU usage. It watches I/O
 usage information output by the Linux kernel (requires 2.6.20 or later)
 and displays a table of current I/O usage by processes on the system.
 Handy for answering the question "Why is my disk churning so much?".
Homepage: http://guichaz.free.fr/iotop/
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  3. IoTop is probably what you're looking for.

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  4. We can find bottleneck in linux server performance using following method..

    1. Take the output of TOP & mem, vmstat commands in one notepad.
    2. Take sar output of 3 months.
    3. check the variation in processes & usage at the time of implementation or change.
    4. If the load is unusual since the change. check for reverting change.
    5. Alternatively one can also check for system & application logs too.

    The above thing will definitely tell us bottleneck..

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  5. I/O bottlenecks can be found using some linux basic commands..And also investigating and comparing their outputs. Read: Understanding Linux IO

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