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https://issues.apache.org/jira/browse/HDFS-3540?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13445159#comment-13445159
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Colin Patrick McCabe commented on HDFS-3540:
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bq. It seems to me that recovery mode and edit log toleration serve different
purposes. The latter is necessary for an HA setup, where admin explicitly set a
small toleration length for tail corruption. The former is useless in an HA
setup and suitable for manual recovery.
"Edit log toleration" is not necessary for an HA setup. In fact, it is
impossible to configure "edit log toleration" together with an HA setup,
because "edit log toleration" is only available in branch-1 (but not later
branches), and HA is only available in branch-2 and later.
bq. Edit log toleration is adequate as is. Recovery mode needs more patches
(more details of errors etc.) to serve the interactive recovery use case better.
Patches are welcome. Check out the design doc for HDFS-3004, which gives an
overview:
https://issues.apache.org/jira/secure/attachment/12542798/recovery-mode.pdf
> Further improvement on recovery mode and edit log toleration in branch-1
> ------------------------------------------------------------------------
>
> Key: HDFS-3540
> URL: https://issues.apache.org/jira/browse/HDFS-3540
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: name-node
> Affects Versions: 1.2.0
> Reporter: Tsz Wo (Nicholas), SZE
> Assignee: Tsz Wo (Nicholas), SZE
>
> *Recovery Mode*: HDFS-3479 backported HDFS-3335 to branch-1. However, the
> recovery mode feature in branch-1 is dramatically different from the recovery
> mode in trunk since the edit log implementations in these two branch are
> different. For example, there is UNCHECKED_REGION_LENGTH in branch-1 but not
> in trunk.
> *Edit Log Toleration*: HDFS-3521 added this feature to branch-1 to remedy
> UNCHECKED_REGION_LENGTH and to tolerate edit log corruption.
> There are overlaps between these two features. We study potential further
> improvement in this issue.
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