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https://issues.apache.org/jira/browse/HBASE-12577?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Enis Soztutar updated HBASE-12577:
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Release Note:
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.
> Disable distributed log replay by default
> -----------------------------------------
>
> Key: HBASE-12577
> URL: https://issues.apache.org/jira/browse/HBASE-12577
> Project: HBase
> Issue Type: Sub-task
> Reporter: Enis Soztutar
> Assignee: Jeffrey Zhong
> Priority: Critical
> Fix For: 0.99.2
>
> Attachments: HBASE-12567.patch, HBASE-12567.patch
>
>
> 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
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