Forum Discussion

Jason_L_40779's avatar
Jason_L_40779
Icon for Nimbostratus rankNimbostratus
Jan 25, 2011

Persistence mirroring H/A

I have question regarding High Availability and persistence hopefully someone with experience can answer. If I failover my active unit, does the user's connection actually break. For example using http, If I have 4 webservers being load balanced using source address persistence, unless i'm mirroring that persistence the users connection I believe will break. Or do I have to do connection mirroring?

 

basic
getting started
new to f5
  • Chris_Miller's avatar
    Chris_Miller
    Icon for Altostratus rankAltostratus
    Jan 25, 2011
    Here's a document describing the best practices around connection and persistence mirroring:

     

     

    https://support.f5.com/kb/en-us/solutions/public/7000/200/sol7222.htmlbestpractice

     

     

    Persistence will keep users going back to the same pool member. If you have a fail-over and aren't mirroring persistence, the user could get send to any server in your pool.

     

     

    Connection mirroring copies actual state data and can add much more overhead. If there was a fail-over in the middle of an HTTP request, the user might see a few objects fail to load but could easily refresh the page. Due to the overhead involved and given how forgiving HTTP is, mirroring connection data for it isn't recommended.

     

     

    If you're using persistence, I'm assuming your application requires it so you should definitely mirror your persistence table to the other unit.