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  1. HBase
  2. HBASE-12567 Track remaining issues for HBase-1.0
  3. HBASE-12577

Disable distributed log replay by default

          Details

          • Type: Sub-task
          • Status: Closed
          • Priority: Critical
          • Resolution: Fixed
          • Affects Version/s: None
          • Fix Version/s: 0.99.2
          • Component/s: None
          • Labels:
            None
          • Hadoop Flags:
            Reviewed
          • Release Note:
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            Disabled Distributed Log Replay (DLR) as default WAL/hlog splitting mechanism. 1.0.x releases will default to Distributed Log Splitting (DLS) system which is the default for 0.98, 0.96 and 0.94 releases.

            DLR improves MTTR (the more regions a server is carrying, the better the improvement. Also, we can start taking writes during WAL/hlog recovery), but rolling upgrade to HBase-1.0.x from earlier releases of 0.98 branch (0.98.0,..,0.98.3) can result in data loss. If you are not doing rolling upgrade, or you are rolling upgrading from a 0.98 greater than or equal to 0.98.4, you can safely turn on distributed log replay by default. Regular upgrade (as opposed to rolling upgrade) is not affected. See HBASE-11094 for details.

            See HBASE-7006 to learn more about DLR. You can enable this feature by setting hbase.master.distributed.log.replay to true in your hbase-site.xml file.
            Show
            Disabled Distributed Log Replay (DLR) as default WAL/hlog splitting mechanism. 1.0.x releases will default to Distributed Log Splitting (DLS) system which is the default for 0.98, 0.96 and 0.94 releases. DLR improves MTTR (the more regions a server is carrying, the better the improvement. Also, we can start taking writes during WAL/hlog recovery), but rolling upgrade to HBase-1.0.x from earlier releases of 0.98 branch (0.98.0,..,0.98.3) can result in data loss. If you are not doing rolling upgrade, or you are rolling upgrading from a 0.98 greater than or equal to 0.98.4, you can safely turn on distributed log replay by default. Regular upgrade (as opposed to rolling upgrade) is not affected. See HBASE-11094 for details. See HBASE-7006 to learn more about DLR. You can enable this feature by setting hbase.master.distributed.log.replay to true in your hbase-site.xml file.

            Description

            Distributed log replay is an awesome feature, but due of HBASE-11094, the rolling upgrade story from 0.98 is hard to explain / enforce.

            The fix for HBASE-11094 only went into 0.98.4, meaning rolling upgrades from 0.98.4- might lose data during the upgrade.

            I feel no matter how much documentation / warning we do, we cannot prevent users from doing rolling upgrades from 0.98.4- to 1.0. And we do not want to inconvenience the user by requiring a two step rolling upgrade.

            Thus I think we should disable dist log replay for 1.0, and re-enable it again for 1.1 (if rolling upgrade from 0.98 is not supported).

            ie. undo: HBASE-10888

              Attachments

              1. HBASE-12567.patch
                1 kB
                Jeffrey Zhong
              2. HBASE-12567.patch
                1 kB
                Enis Soztutar

                Issue Links

                is related to

                Task - A task that needs to be done. HBASE-13584 Disable distributed log replay by default for 1.1

                • Critical - Crashes, loss of data, severe memory leak.
                • Closed

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                    People

                    • Assignee:
                      jeffreyz Jeffrey Zhong
                      Reporter:
                      enis Enis Soztutar
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                      Dates

                      • Created:
                        Updated:
                        Resolved: