Forum Discussion

  • MaCrek_56686's avatar
    MaCrek_56686
    Icon for Altocumulus rankAltocumulus
    Jun 17, 2016

    cron.daily is configured by /etc/anacrontab:

    [root@f5-1:Active:In Sync] config  cat /etc/anacrontab
 /etc/anacrontab: configuration file for anacron

 See anacron(8) and anacrontab(5) for details.

SHELL=/bin/sh
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
 the maximal random delay added to the base delay of the jobs
RANDOM_DELAY=45
 the jobs will be started during the following hours only
START_HOURS_RANGE=3-22

period in days   delay in minutes   job-identifier   command
1       5       cron.daily              nice run-parts /etc/cron.daily
7       25      cron.weekly             nice run-parts /etc/cron.weekly
@monthly 45     cron.monthly            nice run-parts /etc/cron.monthly

    There are interesting options like "START_HOURS_RANGE" or "RANDOM_DELAY". But my cron is not customized, so I suppose, that this is general behavior. Maybe someone else have noticed same behavior.

    • tatmotiv's avatar
      tatmotiv
      Icon for Cirrostratus rankCirrostratus
      Jun 17, 2016
      Interesting. The 12.0 release notes list only one changed behaviour that contains cron: "482950 Phone Home scheduled jobs are now scheduled based on installed time, rather than at default daily/monthly intervals found in cron.daily and cron.monthly."
    • MaCrek_56686's avatar
      MaCrek_56686
      Icon for Altocumulus rankAltocumulus
      Jun 17, 2016
      Output in my previous post is from 12.0.0 HF1. But you are right, on the other box: 11.6.0 HF5, is no /etc/anacron file.
    • tatmotiv's avatar
      tatmotiv
      Icon for Cirrostratus rankCirrostratus
      Jun 17, 2016
      That's what I was looking for, too, but for some reason I cannot find /etc/anacrontab on my systems (vcmp guests running 11.6.0 HF6)... [root@mylb:/S1-green-P:Active:In Sync] config cat /etc/anacrontab cat: /etc/anacrontab: No such file or directory What version / systems are you running?
  • Vijay_E's avatar
    Vijay_E
    Icon for Cirrus rankCirrus
    Jun 17, 2016

    I would recommend that you check the number of connections/HTTP Requests/Throughput around the time of the CPU spike. The graphs for any or all of these variables may show similar pattern. I have usually seen such increase in CPU because of automated backup of database or any other similar application level backup and because the F5 handles these connections via VS, you can see a bump in cpu utilization.

     

  • tatmotiv's avatar
    tatmotiv
    Icon for Cirrostratus rankCirrostratus
    Jun 17, 2016

    You can check your daily jobs by looking at "crontab -l" and the contents of /etc/cron.daily. The CPU peak could also be caused by traffic processing. Do you also see spikes in SSL TPS, connection count or traffic throughput at that time?