Re: NFS Ganesha Active Active Question

Maged Mokhtar <mmokhtar@xxxxxxxxxxx> · Sun, 31 Oct 2021 19:40:51 +0200



    Hi Xiaolong
    The grace period is 90 sec, the failover process should be
      automated and should run quicker than this, maybe like 15-30 sec (
      not too quick to avoid false alarms ), this will make client io
      resume after a small pause.

    
    /Maged

    
    On 31/10/2021 17:37, Xiaolong Jiang
      wrote:

    
      Hi Maged ,
      

      Thank you for the response. That helps a lot! 
      

      Looks like I have to spin up a new server quickly
        and float the ip to the new server. If I spin up the server
        after about 20 mins, I guess IO will recover after that but the
        previous state will be gone since it passed the grace period? 
      

        On Oct 31, 2021, at 4:51 AM, Maged
          Mokhtar <mmokhtar@xxxxxxxxxxx> wrote:

          
          On 31/10/2021 05:29, Xiaolong
            Jiang wrote:

          
            Hi Experts. 
              

              I am a bit confused about ganesha active-active
                setup.
              

              We can set up multiple ganesha servers on top of
                cephfs and clients can point to different ganesh server
                to serve the traffic. that can scale out the traffic. 
              

              From client side, is it using DNS round robin
                directly connecting to ganesha server ?
              Is it possible to front all ganesha server with a
                load balancer so client only connects load balancer IP
                and byte writes can load balancer across all ganesha
                server? 
              

              My current feeling is we probably have to use DNS way
                and specific client read/write request can only go to
                same ganesha server for the session. 

                
                -- 

                
                            Best regards,
                            Xiaolong Jiang
                            

                            Senior Software Engineer at Netflix
                            Columbia University
                          
                        
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          Load balancing ganesha means some clients are being served
            by a gateway and other clients by other gateways, so we
            distribute the clients and their load on the different
            gateways but each client remains on a specific gateway, you
            cannot have a single client load balance on several
            gateways.
          A good way to distribute clients on the gateways is via
            round robin dns, but you do not have, you can distribute ips
            manually among your clients if you want, but dns automates
            the process in scalable way.
          One note about high availability, currently you cannot
            failover clients to another ganesha gateway in case of
            failure, but if you bring the failed gateway back online
            quickly enough, the client connections will resume. So to
            support HA in case a host server failure, the ganesha
            gateways are implemented as containers so you can start the
            failed container on a new host server.
          /Maged  

          
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