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    Redis Failover, No Good Slave

    Scheduled Pinned Locked Moved IT Discussion
    redis
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    • scottalanmillerS
      scottalanmiller
      last edited by

      Increased the slave timeout to 90 seconds. Still nothing.

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      • scottalanmillerS
        scottalanmiller
        last edited by

        Mostly just putting this here for future reference. Still not making any progress.

        https://gennadny.wordpress.com/2015/01/06/meet-redis-masters-slaves-and-scaling-out/

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        • MattSpellerM
          MattSpeller
          last edited by MattSpeller

          For anyone as clueless as I

          "Redis is an open source, BSD licensed, advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs."

          Clarified that right up didn't it 😛

          scottalanmillerS 1 Reply Last reply Reply Quote 1
          • scottalanmillerS
            scottalanmiller @MattSpeller
            last edited by

            @MattSpeller said:

            For anyone as clueless as I

            "Redis is an open source, BSD licensed, advanced key-value cache and store. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets, sorted sets, bitmaps and hyperloglogs."

            Clarified that right up didn't it 😛

            Or much simpler, it is one of the more popular NoSQL databases.

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            • scottalanmillerS
              scottalanmiller
              last edited by

              Redis is also the default database for NodeBB. But Redis doesn't scale like MongoDB and is nowhere near as robust. So MangoLassi runs on MongoDB, not Redis. We are practically the only NodeBB site doing that, though. We are the biggest NodeBB traffic site, as far as I know.

              tonyshowoffT 1 Reply Last reply Reply Quote 0
              • scottalanmillerS
                scottalanmiller
                last edited by

                I should add that this is the command I am using to force a failover:

                SENTINEL failover mymaster
                
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                • scottalanmillerS
                  scottalanmiller
                  last edited by

                  Some docs here but they don't really help...

                  http://objectrocket.com/blog/how-to/introduction-to-redis-sentinel

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                  • mlnewsM
                    mlnews
                    last edited by

                    In cool, ML news, on Duck Duck Go, this thread is the number one search hit for this error. Not very encouraging for finding an answer, but good that ML is getting that kind of SEO now!

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                    • scottalanmillerS
                      scottalanmiller
                      last edited by

                      Other threads of people having the issue but no resolution.

                      http://grokbase.com/t/gg/redis-db/141x9xyjcw/sentinel-2-8-4-nogoodslave-in-manual-failover

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                      • scottalanmillerS
                        scottalanmiller
                        last edited by

                        Here is what the error in the logs looks like...

                        [14804] 04 May 12:12:05.076 # +new-epoch 18
                        [14804] 04 May 12:12:05.076 # +try-failover master mymaster 127.0.0.1 6379
                        [14804] 04 May 12:12:05.078 # +vote-for-leader 78e27a9a509327e6c853535957c808cf8afd50cb 18
                        [14804] 04 May 12:12:05.078 # +elected-leader master mymaster 127.0.0.1 6379
                        [14804] 04 May 12:12:05.078 # +failover-state-select-slave master mymaster 127.0.0.1 6379
                        [14804] 04 May 12:12:05.140 # -failover-abort-no-good-slave master mymaster 127.0.0.1 6379
                        
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                        • scottalanmillerS
                          scottalanmiller
                          last edited by

                          Which really just tells us that it is trying, we already know that it is failing. No additional info in the logs. Pretty useless.

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                          • scottalanmillerS
                            scottalanmiller
                            last edited by

                            Redis doesn't appear to even have this log entry documented:

                            failover-abort-no-good-slave
                            
                            1 Reply Last reply Reply Quote 1
                            • scottalanmillerS
                              scottalanmiller
                              last edited by

                              Working through some ideas here...

                              https://groups.google.com/forum/#!topic/redis-db/M6WPJ0LnaWI

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                              • tonyshowoffT
                                tonyshowoff @A Former User
                                last edited by

                                @thecreativeone91 said:

                                No one wants to be a slave.

                                I was going to say "it's so hard to find a good slave"

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                                • tonyshowoffT
                                  tonyshowoff @scottalanmiller
                                  last edited by tonyshowoff

                                  @scottalanmiller said:

                                  Redis is also the default database for NodeBB. But Redis doesn't scale like MongoDB and is nowhere near as robust. So MangoLassi runs on MongoDB, not Redis. We are practically the only NodeBB site doing that, though. We are the biggest NodeBB traffic site, as far as I know.

                                  I kept reading for a long time that Redis was hot shoot in a champaign glass, and we tested replacing some memcached servers and some MongoDB servers with it and I have to say that we realised there were problems fairly quickly. I liked how setting up different parts of Redis was easier, however there were huge latency issues and scalability problems as far as clustering/slaving went that caused us to go back to MongoDB.

                                  I should note that now though we're moving away from MongoDB to Cassandra, which works a lot better and actually scales even better than MongoDB and doesn't suffer from the strange paging issue (with millions of documents) that MongoDB does, i.e. works fairly well.

                                  Right now many things are using both until we can transfer old data from our MongoDB servers to Cassandra, but it's a few dozen terabytes of data.

                                  I'm here to say that Redis may work for some, but as far as I'm concerned, compared to memcached (it'd be nice if it did have clustering, though) and MongoDB or Cassandra, it's cold diarrhoea in a dixie cup.

                                  scottalanmillerS 1 Reply Last reply Reply Quote 1
                                  • scottalanmillerS
                                    scottalanmiller
                                    last edited by

                                    Yup, we did the same move from MongoDB to Cassandra at Change. Although MongoDB 3 is supposed to be a big leap forward.

                                    Redis appears to be a complete disaster, however.

                                    1 Reply Last reply Reply Quote 1
                                    • scottalanmillerS
                                      scottalanmiller @tonyshowoff
                                      last edited by

                                      @tonyshowoff said:

                                      I'm here to say that Redis may work for some, but as far as I'm concerned, compared to memcached (it'd be nice if it did have clustering, though) and MongoDB or Cassandra, it's cold diarrhoea in a dixie cup.

                                      That's definitely how I am seeing it at this point.

                                      1 Reply Last reply Reply Quote 1
                                      • scottalanmillerS
                                        scottalanmiller
                                        last edited by

                                        One of the biggest issues is the lack of logging. Things fail, no explanation why. Just "go figure it out". The documentation is abysmal and it appears that no one is using it. Do a search and you can only find their own useless, internal docs.

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