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Dinesh3888's avatar
Dinesh3888
Icon for Nimbostratus rankNimbostratus
Mar 30, 2015

Priority Group Issue

Hi,

 

I have a setup in which a pool contains 2 server. ServerA and serverB. Server A has priority 1 and its active only if it fails ServerB with priority 0 will come as active. we have a source based persistence. I faced a situation in which server A went down and all the request moved automatically to serverB as expected but after serverA recovered and became active, still the persistence request was going only to serverB. This was due to Persistence. when we removed persistence the serverA was getting the traffic and ServerB became idle. Is there any way to make this Customised, because we cannot remove persistence for that application and this makes huge impact.

 

3 Replies

  • bhs_114985's avatar
    bhs_114985
    Historic F5 Account
    Mar 30, 2015

    If server B is the only other server in the pool and only active when A is down why do you need persistence at all given 1 server is only ever active? If you still want to use persistence for some reason you could do an iRule like this from this post: selective-persistence-with-priority-grouping

    when LB_SELECTED {
if { [LB::server priority] eq 0 } {
persist none }
else { persist source_addr 255.255.255.255 3600 }
}
    • Dinesh3888's avatar
      Dinesh3888
      Icon for Nimbostratus rankNimbostratus
      Apr 02, 2015
      Thanks bhs,i will get the Irule tested. Yes as per this scenario we don't need persistence, This is QA testing environment. i will get multiple servers added later to the group.
  • dragonflymr's avatar
    dragonflymr
    Icon for Cirrostratus rankCirrostratus
    Mar 31, 2015

    Hi,

     

    What you described is by design. Connections persisting to ServerB will be directed to ServerB even after ServerA is back up. Only new connections will be sent to serverA, still no new connections will be send to serverB. After some time (when persistence records will expire) there should be no active connection handled by serverB. Anyway, with only one server active in pool there is no big reason to have persistence - except if this is future proof design - so some new pool members will be added with priority 1 later on.

     

    Piotr