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https://issues.apache.org/jira/browse/HADOOP-2585?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Konstantin Shvachko updated HADOOP-2585:
----------------------------------------
Attachment: SecondaryStorage.patch
This is a new patch that
# does not contain code that was fixed in HADOOP-3069;
# fixes findbugs from the previous run;
# fixes TestCheckpoint failure.
The letter was tricky. TestCheckpoint failed on Hudson but not on any of other
machines I tested it. The failure is related to that when the name-node started
it did not get an exclusive lock for its storage directory as required. I
initially suspected that this is a Solaris problem, but later realized that it
is a NFS problem, which may not support exclusive locks consistently.
IMO we should enforce exclusivity of locks only if it is supported by a local
file system.
So the test now checks whether exclusive locks are supported before failing.
> Automatic namespace recovery from the secondary image.
> ------------------------------------------------------
>
> Key: HADOOP-2585
> URL: https://issues.apache.org/jira/browse/HADOOP-2585
> Project: Hadoop Core
> Issue Type: New Feature
> Components: dfs
> Affects Versions: 0.16.0
> Reporter: Konstantin Shvachko
> Assignee: Konstantin Shvachko
> Attachments: SecondaryStorage.patch, SecondaryStorage.patch
>
>
> Hadoop has a three way (configuration controlled) protection from loosing the
> namespace image.
> # image can be replicated on different hard-drives of the same node;
> # image can be replicated on a nfs mounted drive on an independent node;
> # a stale replica of the image is created during periodic checkpointing and
> stored on the secondary name-node.
> Currently during startup the name-node examines all configured storage
> directories, selects the
> most up to date image, reads it, merges with the corresponding edits, and
> writes to the new image back
> into all storage directories. Everything is done automatically.
> If due to multiple hardware failures none of those images on mounted hard
> drives (local or remote)
> are available the secondary image although stale (up to one hour old by
> default) can be still
> used in order to recover the majority of the file system data.
> Currently one can reconstruct a valid name-node image from the secondary one
> manually.
> It would be nice to support an automatic recovery.
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