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From "Jonathan Hsieh (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7987) Snapshot Manifest file instead of multiple empty files
Date Fri, 29 Mar 2013 15:49:15 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7987?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13617445#comment-13617445
] 

Jonathan Hsieh commented on HBASE-7987:
---------------------------------------

[~mbertozzi], have you considered writing this manifest data to a snapshots hbase table instead
of the file system? 

Pros: no small files, likely less need for an external snapshot info viewer, 
Cons: lose ability to export only looking at file system (but can be done with a single hbase
read/scan)

It also seems to be a reasonable place to prototype the one row-one snapshot (later table),
cols are regions layout.

                
> 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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