[HBASE-5360] [uberhbck] Add options for how to handle offline split parents.

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.90.7, 0.92.1, 0.94.0
• Fix Version/s: 0.94.1, 0.95.0
• Component/s: hbck
• Hadoop Flags: Reviewed
• Assignee: Jimmy Xiang
• Reporter: Jonathan Hsieh
• Created: 09/Feb/12 00:56
• Updated: 26/Feb/13 08:15
• Resolved: 17/Jun/12 23:56

Description

In a recent case, we attempted to repair a cluster that suffered from HBASE-4238 that had about 6-7 generations of "leftover" split data. The hbck repair options in an development version of HBASE-5128 treat HDFS as ground truth but didn't check SPLIT and OFFLINE flags only found in meta. The net effect was that it essentially attempted to merge many regions back into its eldest geneneration's parent's range.

More safe guards to prevent "mega-merges" are being added on HBASE-5128.

This issue would automate the handling of the "mega-merge" avoiding cases such as "lingering grandparents". The strategy here would be to add more checks against .META., and perform part of the catalog janitor's responsibilities for lingering grandparents. This would potentially include options to sideline regions, deleting grandparent regions, min size for sidelining, and mechanisms for cleaning .META..

Note: There already exists an mechanism to reload these regions – the bulk loaded mechanisms in LoadIncrementalHFiles can be used to re-add grandparents (automatically splitting them if necessary) to HBase.

Issue Links

• is related to: HBASE-6223 Document hbck improvements: HBASE-6173, HBASE-5360
• relates to: HBASE-5719 Enhance hbck to sideline overlapped mega regions
• relates to: HBASE-6223 Document hbck improvements: HBASE-6173, HBASE-5360