Re: thin arbiter vs standard arbiter

Dmitry Melekhov <dm@xxxxxxxxxx> · Thu, 2 Aug 2018 15:29:41 +0400



    01.08.2018 22:04, Amar Tumballi пишет:

    
        This recently added document talks about some of the
            technicalities of the feature:
          

          https://docs.gluster.org/en/latest/Administrator%20Guide/Thin-Arbiter-Volumes/
          

          Please go through and see if it answers your questions.
          

          -Amar
        
      
    Hello!

    
    I have question:

    
    Manual says:

    
    "When one brick is up: Fail FOP with EIO."

    
    So, if we have 2 nodes with thin arbiter and only one node is up,
    i.e. second node is down for some reason, then I/O will be stopped.

    Any reasons to have two nodes then?

    
    Could you tell me is manual right here or it is misprint?

    
    Thank you!

    
            On Wed, Aug 1, 2018 at 11:09 PM,
              wkmail <wkmail@xxxxxxxxx>
              wrote:

              I see mentions of thin
                arbiter in the 4.x notes and I am intrigued.

                
                As I understand it, the thin arbiter volume is

                
                a) receives its data on an async basis (thus it can be
                on a slower link). Thus gluster isn't waiting around to
                verify if it actually got the data.

                
                b) is only consulted in situations where Gluster needs
                that third vote, otherwise it is not consulted.

                
                c) Performance should therefore be better because
                Gluster is only seriously talking to 2 nodes instead of
                3 nodes (as in normal arbiter or rep 3)

                
                Am I correct?

                
                If so, is thin arbiter ready for production or at least
                use on non-critical workloads?

                
                How safe is it for VMs images (and/or VMs with
                sharding)?

                
                How much faster is thin arbiter setup over a normal
                arbiter given that the normal data only really sees the
                metadata?

                
                In a degraded situation (i.e. loss of one real node),
                would having a thin arbiter on a slow link be
                problematic until everything is healed and returned to
                normal?

                
                Sincerely,

                
                -wk

                
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            -- 

            
                    Amar Tumballi (amarts)

                    
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