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IOWait Issue

Discussion in 'General Discussion' started by ManageMyService, Feb 2, 2005.

  1. ManageMyService

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    Have some crazy iowait issues here...


    14:42:14 up 1:09, 1 user, load average: 8.37, 2.23, 0.96
    139 processes: 138 sleeping, 1 running, 0 zombie, 0 stopped
    CPU states: cpu user nice system irq softirq iowait idle
    total 0.0% 0.0% 100.0% 0.0% 0.0% 100.0% 0.0%
    cpu00 0.0% 0.0% 100.0% 0.0% 0.0% 0.0% 0.0%
    cpu01 0.0% 0.0% 0.0% 0.0% 0.0% 100.0% 0.0%
    Mem: 993108k av, 944012k used, 49096k free, 0k shrd, 75532k buff
    356072k actv, 409756k in_d, 17848k in_c
    Swap: 979956k av, 24396k used, 955560k free 646852k cached

    PID USER PRI NI SIZE RSS SHARE STAT %CPU %MEM TIME CPU COMMAND
    1 root 15 0 464 436 408 S 0.0 0.0 0:04 0 init
    2 root RT 0 0 0 0 SW 0.0 0.0 0:00 0 migration/0
    3 root RT 0 0 0 0 SW 0.0 0.0 0:00 1 migration/1
    4 root 15 0 0 0 0 SW 0.0 0.0 0:00 0 keventd
    5 root 34 19 0 0 0 SWN 0.0 0.0 0:00 0 ksoftirqd/0
    6 root 34 19 0 0 0 SWN 0.0 0.0 0:00 1 ksoftirqd/1
    9 root 15 0 0 0 0 SW 0.0 0.0 0:00 1 bdflush
    7 root 15 0 0 0 0 SW 0.0 0.0 0:01 0 kswapd
    8 root 15 0 0 0 0 SW 0.0 0.0 0:03 1 kscand
    10 root 15 0 0 0 0 SW 0.0 0.0 0:00 0 kupdated
    11 root 25 0 0 0 0 SW 0.0 0.0 0:00 0 mdrecoveryd
    15 root 15 0 0 0 0 DW 0.0 0.0 0:11 1 kjournald
    483 root 15 0 0 0 0 SW 0.0 0.0 0:00 0 kjournald
    911 root 15 0 556 532 472 D 0.0 0.0 0:00 0 syslogd
    915 root 15 0 456 444 392 S 0.0 0.0 0:00 1 klogd
    925 root 15 0 452 444 388 S 0.0 0.0 0:00 0 irqbalance
    954 root 15 0 392 376 332 S 0.0 0.0 0:00 1 mdadm
    2005 root 15 0 1148 744 652 S 0.0 0.0 0:00 0 cupsd
    2060 named 25 0 3020 2820 1740 S 0.0 0.2 0:02 1 named
    2074 root 15 0 880 792 628 S 0.0 0.0 0:00 0 sshd
    2088 root 15 0 696 656 580 S 0.0 0.0 0:00 0 xinetd
    2106 root 17 0 2244 1364 960 S 0.0 0.1 0:00 0 chkservd
    2243 root 15 0 640 632 536 S 0.0 0.0 0:00 0 crond
    2280 root 25 0 1152 1016 1012 S 0.0 0.1 0:00 0 mysqld_safe
    2392 mysql 15 0 44096 40M 1408 S 0.0 4.1 1:02 1 mysqld
    2459 mailnull 15 0 3400 3352 1004 S 0.0 0.3 0:00 0 eximstats
    2469 nobody 24 0 1172 1172 444 S 0.0 0.1 0:00 0 entropychat
    2473 nobody 25 0 612 612 380 S 0.0 0.0 0:00 1 melange
    2521 root 15 0 988 984 696 S 0.0 0.0 0:00 0 pure-ftpd
    2525 root 25 0 616 616 432 S 0.0 0.0 0:00 0 pure-authd
    2527 cpanel 25 0 812 812 536 S 0.0 0.0 0:00 1 stunnel-4.04loc
    2574 root 25 0 468 468 396 S 0.0 0.0 0:00 0 portsentry
    2596 root 22 0 404 404 352 S 0.0 0.0 0:00 1 mingetty
    2597 root 22 0 408 408 352 S 0.0 0.0 0:00 0 mingetty
    2598 root 22 0 408 408 352 S 0.0 0.0 0:00 0 mingetty
    2600 root 22 0 404 404 352 S 0.0 0.0 0:00 0 mingetty
    2601 root 22 0 408 408 352 S 0.0 0.0 0:00 1 mingetty
    2602 root 22 0 408 408 352 S 0.0 0.0 0:00 1 mingetty
    2613 root 15 0 0 0 0 SW 0.0 0.0 0:00 1 loop0
    3031 root 15 0 0 0 0 SW 0.0 0.0 0:00 1 kjournald
    3803 root 15 0 1256 1164 824 S 0.0 0.1 0:01 1 sshd
    3805 root 15 0 1324 1300 1116 S 0.0 0.1 0:00 1 bash
    11207 root 35 19 5304 4704 1544 S N 0.0 0.4 0:00 1 cpanellogd


    See how the server is doing nothing and the iowait has just suddenly shot up...server loads were extremely low and then all of a sudden the iowait shoots up and the server crashes.

    I'm thinking it's a hardware issue, or does anyone think there is another problem here?
     
  2. ManageMyService

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    Also, kernel is the latest in the 2.4 series and running CentOS....should I go to 2.6 maybe?
     
  3. ManageMyService

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    Have built 2.6 kernel and am testing now...
     
  4. chirpy

    chirpy Well-Known Member

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    Go on, have a guess
    That's very odd behaviour. It'll be interesting if the 2.6 kernel fixes it, otherwise it could well be a BIOS/HW/driver issue.
     
  5. ManageMyService

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    This kernel is bad: 2.4.21-27.0.2.ELsmp

    We installed it on 4 servers and all 4 crashed with the iowait issue. A upgrade to 2.6 appears to resolve the issue, interestingly enough a downgrade also resolves the issue. There's a definite issue with this kernel version.

    Gonna say case closed for now :)
     
  6. chirpy

    chirpy Well-Known Member

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    If it's a reproducable problem then you might like to report it to RedHat as I'm sure they'd be interested. I've certainly used than kernel on many servers of all different types and not seen an IOWAIT problem like that - makes me wonder if it might be a driver or hardware compatibility issues, then.
     
  7. DigitalN

    DigitalN Well-Known Member

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    I haven't seen anything majorly strange with that kernel either on a few boxes running it.

    BTW:

    2005 root 15 0 1148 744 652 S 0.0 0.0 0:00 0 cupsd

    You don't really want that to be running. Sorry i couldn't help myself. :)
     
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