6 Replies Latest reply on Dec 27, 2017 3:22 PM by sraposo

    Failover mechanism when using Network Load Balancing

    Saken

      Hi,

      can someone explain in detail of Failover mechanism (PI AF Application Server HA) when using Network Load Balancing,

      I mean what's going on when PI AF Application service going down or unavailable on one of AF servers and what Network Load Balancer does in this case?

       

      thanks,

      Saken

        • Re: Failover mechanism when using Network Load Balancing
          Kenji Hashimoto

          What Network Load balancer will you use?

          There are multiple ways to achieve NLB.

          ・Windows Network Load Balancing (Windows Role and features)

          ・Heard ware Network Load Balancer

          ・Cloud vendor's NLB

           

          I believe it depends on which NLB will you use.

           

          This KB explains HA options for AF.

          KB00634 - High Availability (HA) options for PI Asset Framework (PI AF)

          https://techsupport.osisoft.com/Troubleshooting/KB/KB00634

          Microsoft documentation is also helpful.

          Network Load Balancing Overview

          >I mean what's going on when PI AF Application service going down or unavailable on one of AF servers and what Network Load Balancer does in this case?

          By default, Windows Network Load Balancing does not monitor service level. It monitors NIC level availability.

          So, if the one of the machine's AF Service is shutdown, it could not detect it and there are possibilities that the Windows Network Load Balancing passes the access to the machine that AF service is stopping.

          If you want to avoid it, you need to implement it by yourself.

          For example

          Monitoring Application Level Health (Windows)

          There should be Network Load Balancers vendors that provide NLB with monitoring service level health function. I am not familiar with it though.