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fxn-f5-bot_3543's avatar
fxn-f5-bot_3543
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Feb 28, 2018
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Delayed Fail over to a secondary server

Hi All,   I have a unique requirement where the client would like to have a delayed fail over between 2 nodes in a pool. There will be a database application behind an LTM with a pool containing 2...
application delivery
BIG-IP DNS
LTM
  • Hannes_Rapp_162's avatar
    Hannes_Rapp_162
    Feb 28, 2018

    Seems like all you need is a ratio configuration to make sure your primary DB node gets all connections as long as its available, and a health-check monitor. Maybe even tcp-half-open healt-check monitor will do. As long as the Standby Database Node keeps its TCP listener closed while it's sub-services are unavailable, you will not need any complex alchemy. That's how most database systems operate - if service is down, TCP listener is closed. BigIP can identify this and not send any traffic there. What DB system are you using?

     

    https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-monitors-reference-11-2-0/1.html

     

Hannes_Rapp's avatar
Hannes_Rapp
Icon for Nimbostratus rankNimbostratus
Feb 28, 2018

Seems like all you need is a ratio configuration to make sure your primary DB node gets all connections as long as its available, and a health-check monitor. Maybe even tcp-half-open healt-check monitor will do. As long as the Standby Database Node keeps its TCP listener closed while it's sub-services are unavailable, you will not need any complex alchemy. That's how most database systems operate - if service is down, TCP listener is closed. BigIP can identify this and not send any traffic there. What DB system are you using?

 

https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/ltm-monitors-reference-11-2-0/1.html

 

  • fxn-f5-bot_3543's avatar
    fxn-f5-bot_3543
    Icon for Nimbostratus rankNimbostratus
    Feb 28, 2018

    Hi Hannes,

     

    Many thanks for your response. It kind of makes sense, as long as the secondary passive DB server is not listening on its service port the F5 will declare the node as down and will not forward any traffic. I will confirm with the client if this is the case (Though I don't see a reason why would someone run a service on a passive DB server). This is a Sybase database, now probably part of the SAP platform.

     

    Thanks for your help. Regards