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Thread: High I/O?

  1. #1
    Join Date
    Dec 2003
    Posts
    92

    High I/O?

    What is considered to be high disk I/O?

    Here's what I have in cPanel

    Device Trans./Sec Blocks Read/sec Blocks Written/Sec Total Blocks Read Total Blocks Written
    sdb 17.34 28.97 205.08 1258108 8906492
    sdb1 0.01 0.03 0.00 1214 4
    sdb2 16.84 15.99 120.88 694646 5249768
    sdb3 6.32 8.89 48.33 386190 2099064
    sdb5 1.59 2.83 12.05 122762 523288
    sdb6 0.01 0.02 0.00 980 0
    sdb7 2.13 1.14 15.77 49550 684992
    sdb8 1.02 0.06 8.04 2726 349376



    And I think it's going really slow because of disk writes... but do these numbers support that theory?

  2. #2
    Join Date
    Dec 2003
    Posts
    92
    I just ran "sudo hdparm -t /dev/sdb7"... that's the drive that has my /home directory.. and this is what I got

    84 MB in 3.02 seconds = 27.86 MB/sec

    Is that really slow?

    I ran it again and got

    160 MB in 3.05 seconds = 52.47 MB/sec

  3. #3
    Join Date
    Nov 2003
    Location
    Toronto, Ontario
    Posts
    641
    what does /usr/bin/sar say for iowait?
    Kevin

  4. #4
    Join Date
    Dec 2003
    Posts
    92
    What command do I use to get that?

  5. #5
    Join Date
    Mar 2006
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    /usr/bin/sar

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  6. #6
    Join Date
    Dec 2004
    Posts
    223
    Higher the disk read speed, better it is. But when the load is high, or if there are more I/O bound applications hdparm could give low speed..
    Try it when there arent much applications waiting on I/O, to check for any possible hardware issue.
    Or check which are the processes in the 'D' state. Such processes are mostly on IO wait..
    The fear of the LORD is the beginning of knowledge

    There is no system but GNU, and Linux is one of its kernels!

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