[HBASE-6236] Offline meta repair fails if the HBase base mount point is on a different cluster/volume than its parent in a ViewFS or similar FS

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.94.1, 0.95.0
• Component/s: hbck
• Hadoop Flags: Reviewed

Release Note

-sidelineDir option has been added to both hbck and OfflineMetaRepair.
It allows specification of hdfs directory where offlined data is stored.

• Assignee: Aditya Kishore
• Reporter: Aditya Kishore
• Created: 19/Jun/12 01:56
• Updated: 26/Feb/13 08:16
• Resolved: 23/Jun/12 16:20

Description

While building the .META. and -ROOT- from FS data alone (HBASE-4377), hbck tries to move the existing .META. and -ROOT- directories to a backup folder.

This backup folder is created at the same level as the base HBase folder (e.g. /hbase-xxxxxx if the base HBase folder is '/hbase').

In a federated HDFS like ViewFS and other similar FS implementations, it is not possible to rename files/directories across namespace volumes (ViewFS guide section 3.5) and as a result hbck crashes.

A solution to this problem is to create the backup directory under the folder where HBase base folder has been mounted. This ensures that source and destination of rename operation are on the same namespace volume.

Patch for 0.94 and trunk is attached for review. The patch modifies the location of the backup directory from '/hbase-xxxxxxx' to '/hbase/.hbcktmp-xxxxxxx'