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https://issues.apache.org/jira/browse/HBASE-50?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Li Chongxin updated HBASE-50:
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Attachment: HBase Snapshot Design Report V3.pdf
Design document has been updated based on the discussion. Following changes
have been made:
* Requirements have been updated
* Snapshot can now be created for both online (enabled) tables and offline
(disabled) tables. For offline table, snapshot is performed by the master
* Metadata for the table is not copied from .regioninfo any more but totally
dumped from .META.
* WAL logs are now archived instead of deleted, so snapshot does not copy the
log files any more but take a file that lists the log names. A new section 6.5
is added on log maintenance
* Rename 'reference' family in .META. to 'snapshot'
* Add the same column family 'snapshot' to -ROOT- so that .META. can be
snapshot too
* A new file .snapshotinfo is created under each snapshot dir to keep the meta
information of snapshot. List operation for snapshots will read the this meta
file.
* A new operation 'Restore' is added to restore a table from a snapshot on the
same data center
* Export and import are changed. Export and import are used to export a
snapshot to or imort a snapshot from other data centers. Therefore, exported
snapshot has the same file format as how a table is exported so that we can
treat exported snapshot the same as exported table and import the exported
snapshot with the same import facility.
Pending Questions:
1.
What if the table with the same name is still online when we want to restore a
snapshot? There will be a name collision in both HDFS and .META. ; We should
not touch the existing table, right?
2.
Then shall we allow rename the snapshot as a new table name? For example the
snapshot is created for table "table1", can we restore the snapshot as "table2"?
> 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, snapshot-src.zip
>
>
> 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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