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Dazzla_20011's avatar
Dazzla_20011
Icon for Nimbostratus rankNimbostratus
Feb 21, 2011

Arguments for monitor timeout set to 3 times interval

Hi,

 

 

I've created an external monitor to monitor bbc & google every 15 seconds via a proxy.

 

The project manager would like me to reduce the timeout from 3 times the monitor interval to 2 times the monitor interval so the failover time is reduced.

 

 

I would like to stick with the recommended 3 times but need some reasons to support my aurgument?

 

 

Thanks

 

Darren

 

 

  • What are your reasons for wanting to stick with 3x? Those settings should be tailored to fail-over requirements and application responsiveness.
  • nathe's avatar
    nathe
    Icon for Cirrocumulus rankCirrocumulus
    Dazzla

     

     

    I agree with Chris, it's all about configuring an "appropriate" interval / timeout ratio and it takes all sorts.

     

     

    N
  • Really just becuase the documentation reommends 3x. Only concern is I wouldn't want any false positives which would mark a pool member as down.

     

    I suppose the interval is very 15 seconds so we should be OK to use 2x.

     

     

    Thanks
  • nathe's avatar
    nathe
    Icon for Cirrocumulus rankCirrocumulus
    How about every 10secs whilst having 3x? This would still be the same time as 15secs 2x but an extra check for good measure. Again, and I have to refer to Chris' post here, the timeouts need to be tailored to application response times. If the app needs 15secs or more then go with what the PM asks, no point configuring a monitor interval lower that's going to struggle to be a success.

     

     

    N
  • I'm using a bashscript to check internet availability via two bluecoat proxies, my concern is reducing the interval will increase CPU usage on the F5 and also the additional overhead on the firewalls and bluecoats. The other problem is they would like this one particular app to always use the same proxy. To get around this I've created another Pool and increased the prioirty on one of the Pool members.

     

    Would it be possible to use an i-rule for this particular app which would simpy state traffic from source x.x.x.x always use Pool member A unless it becomes unavailable. if I could do this I wouldn't need two seperate Pools so could then reduce the monitor interval?

     

     

    Many Thanks

     

    Darren