Find the answer to your Linux question:
Results 1 to 3 of 3
We are having a performance problem with one of our servers, and when I read the output from sar it appears the %iowait is high. But when I look at ...
Enjoy an ad free experience by logging in. Not a member yet? Register.
  1. #1
    Just Joined!
    Join Date
    Sep 2008
    Posts
    3

    iowait question


    We are having a performance problem with one of our servers, and when I read the output from sar it appears the %iowait is high. But when I look at individual cpu's, the %iowait is fine. Can someone tell me why the Average %iowait is so high, but individual cpu's are fine? Thanks!


    CPU %user %nice %system %iowait %idle
    all 23.70 0.00 31.08 45.21 0.00
    0 0.10 0.00 0.03 0.00 99.87
    1 0.29 0.00 0.07 0.13 99.52
    2 0.03 0.00 0.07 0.07 99.82
    3 0.10 0.00 0.23 0.03 99.65
    4 0.05 0.00 0.42 0.63 98.90
    5 0.03 0.00 0.09 0.47 99.41
    6 0.02 0.00 0.00 0.00 99.98
    7 0.07 0.00 0.02 0.01 99.89

  2. #2
    Linux Guru coopstah13's Avatar
    Join Date
    Nov 2007
    Location
    NH, USA
    Posts
    3,149
    that is interesting, check the output of vmstat or iostat
    Code:
    vmstat -n 1 10
    iostat -d -x 1 10

  3. #3
    Just Joined!
    Join Date
    Sep 2008
    Posts
    3
    Thanks. I should have mentioned that I've used those commands but the wait time shows also very low. I just can't understand why the %iowait average using sar shows so high but the other commands don't verify this. The other thing is that the high iowait times do seem to coincide with system responsiveness.

  4. $spacer_open
    $spacer_close

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •