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https://issues.apache.org/jira/browse/HBASE-50?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12897144#action_12897144
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HBase Review Board commented on HBASE-50:
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Message from: "Chongxin Li" <[email protected]>
bq. On 2010-08-10 10:04:44, Ted Yu wrote:
bq. > src/main/java/org/apache/hadoop/hbase/master/HMaster.java, line 962
bq. > <http://review.cloudera.org/r/467/diff/3/?file=6015#file6015line962>
bq. >
bq. > It would be better to move crashed snapshots into a separate
directory under snapshot rootDir.
If so, probably we need the above method.
But why move crashed snapshots into a separate directory? It would be pretty
hard to recover a crashed snapshot.
bq. On 2010-08-10 10:04:44, Ted Yu wrote:
bq. > src/main/java/org/apache/hadoop/hbase/master/HMaster.java, line 945
bq. > <http://review.cloudera.org/r/467/diff/3/?file=6015#file6015line945>
bq. >
bq. > If you create directory for failed snapshots, you can also add
listFailedSnapshots() method.
Currently there is no directory for failed snapshots. If snapshot fails, it is
cleaned up and exception is thrown to notify the user.
bq. On 2010-08-10 10:04:44, Ted Yu wrote:
bq. > src/main/java/org/apache/hadoop/hbase/master/HMaster.java, line 930
bq. > <http://review.cloudera.org/r/467/diff/3/?file=6015#file6015line930>
bq. >
bq. > Do we need to abort TableSnapshot processing in case of exception ?
For snapshot which is created by TableSnapshot, the table must be offline and
snapshot is totally driven by the master. Region servers have no awareness of
such a snapshot. So in case of exception, just clean up the failed snapshot.
There is no need to abort the snapshot across the cluster.
Regarding SnapshotMonitor, it only monitors the snapshots which are created
across the region servers.
- Chongxin
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> Snapshot of table
> -----------------
>
> Key: HBASE-50
> URL: https://issues.apache.org/jira/browse/HBASE-50
> Project: HBase
> Issue Type: New Feature
> Reporter: Billy Pearson
> Assignee: Li Chongxin
> Priority: Minor
> Attachments: HBase Snapshot Design Report V2.pdf, HBase Snapshot
> Design Report V3.pdf, HBase Snapshot Implementation Plan.pdf, Snapshot Class
> Diagram.png
>
>
> Havening an option to take a snapshot of a table would be vary useful in
> production.
> What I would like to see this option do is do a merge of all the data into
> one or more files stored in the same folder on the dfs. This way we could
> save data in case of a software bug in hadoop or user code.
> The other advantage would be to be able to export a table to multi locations.
> Say I had a read_only table that must be online. I could take a snapshot of
> it when needed and export it to a separate data center and have it loaded
> there and then i would have it online at multi data centers for load
> balancing and failover.
> I understand that hadoop takes the need out of havening backup to protect
> from failed servers, but this does not protect use from software bugs that
> might delete or alter data in ways we did not plan. We should have a way we
> can roll back a dataset.
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