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https://issues.apache.org/jira/browse/HBASE-7987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617465#comment-13617465
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Matteo Bertozzi commented on HBASE-7987:
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I don't like having a table for tracking snapshots alone.
We've already discussed about having a "global" file tracking table, that
allows you to describe tables and snapshots. This will have the advantage of
not having the half fs or meta state on failures, and allows to remove all the
references and link files that doesn't really make sense.
I see this jira more as a "improve the current situation", without having to
change much of the current design.
also as you mentioned we lose the ability to export a snapshot with hbase down,
and we don't get any big advantage.
> Snapshot Manifest file instead of multiple empty files
> ------------------------------------------------------
>
> Key: HBASE-7987
> URL: https://issues.apache.org/jira/browse/HBASE-7987
> Project: HBase
> Issue Type: Improvement
> Components: snapshots
> Reporter: Matteo Bertozzi
> Attachments: HBASE-7987.sketch, HBASE-7987-v2.sketch
>
>
> Currently taking a snapshot means creating one empty file for each file in
> the source table directory, plus copying the .regioninfo file for each
> region, the table descriptor file and a snapshotInfo file.
> during the restore or snapshot verification we traverse the filesystem
> (fs.listStatus()) to find the snapshot files, and we open the .regioninfo
> files to get the information.
> to avoid hammering the NameNode and having lots of empty files, we can use a
> manifest file that contains the list of files and information that we need.
> To keep the RS parallelism that we have, each RS can write its own manifest.
> {code}
> message SnapshotDescriptor {
> required string name;
> optional string table;
> optional int64 creationTime;
> optional Type type;
> optional int32 version;
> }
> message SnapshotRegionManifest {
> optional int32 version;
> required RegionInfo regionInfo;
> repeated FamilyFiles familyFiles;
> message StoreFile {
> required string name;
> optional Reference reference;
> }
> message FamilyFiles {
> required bytes familyName;
> repeated StoreFile storeFiles;
> }
> }
> {code}
> {code}
> /hbase/.snapshot/<snapshotName>
> /hbase/.snapshot/<snapshotName>/snapshotInfo
> /hbase/.snapshot/<snapshotName>/<tableName>
> /hbase/.snapshot/<snapshotName>/<tableName>/tableInfo
> /hbase/.snapshot/<snapshotName>/<tableName>/regionManifest(.n)
> {code}
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