This is the documentation for Cloudera Enterprise 5.8.x. Documentation for other versions is available at Cloudera Documentation.

Checking and Repairing HBase Tables

HBaseFsck (hbck) is a command-line tool that checks for region consistency and table integrity problems and repairs corruption. It works in two basic modes — a read-only inconsistency identifying mode and a multi-phase read-write repair mode.
  • Read-only inconsistency identification: In this mode, which is the default, a report is generated but no repairs are attempted.
  • Read-write repair mode: In this mode, if errors are found, hbck attempts to repair them.

You can run hbck manually or configure the hbck poller to run hbck periodically.

Always run HBase administrative commands such as the HBase Shell, hbck, or bulk-load commands as the HBase user (typically hbase).

Running hbck Manually

The hbck command is located in the bin directory of the HBase install.
  • With no arguments, hbck checks HBase for inconsistencies and prints OK if no inconsistencies are found, or the number of inconsistencies otherwise.
  • With the -details argument, hbck checks HBase for inconsistencies and prints a detailed report.
  • To limit hbck to only checking specific tables, provide them as a space-separated list: hbck <table1> <table2>
  Warning: The following hbck options modify HBase metadata and are dangerous. They are not coordinated by the HMaster and can cause further corruption by conflicting with commands that are currently in progress or coordinated by the HMaster. Even if the HMaster is down, it may try to recover the latest operation when it restarts. These options should only be used as a last resort. The hbck command can only fix actual HBase metadata corruption and is not a general-purpose maintenance tool. Before running these commands, consider contacting Cloudera Support for guidance. In addition, running any of these commands requires an HMaster restart.
  • If region-level inconsistencies are found, use the -fix argument to direct hbck to try to fix them. The following sequence of steps is followed:
    1. The standard check for inconsistencies is run.
    2. If needed, repairs are made to tables.
    3. If needed, repairs are made to regions. Regions are closed during repair.
  • You can also fix individual region-level inconsistencies separately, rather than fixing them automatically with the -fix argument.
    • -fixAssignments repairs unassigned, incorrectly assigned or multiply assigned regions.
    • -fixMeta removes rows from hbase:meta when their corresponding regions are not present in HDFS and adds new meta rows if regions are present in HDFS but not in hbase:meta.
    • -repairHoles creates HFiles for new empty regions on the filesystem and ensures that the new regions are consistent.
    • -fixHdfsOrphans repairs a region directory that is missing a region metadata file (the .regioninfo file).
    • -fixHdfsOverlaps fixes overlapping regions. You can further tune this argument using the following options:
      • -maxMerge <n> controls the maximum number of regions to merge.
      • -sidelineBigOverlaps attempts to sideline the regions which overlap the largest number of other regions.
      • -maxOverlapsToSideline <n> limits the maximum number of regions to sideline.
  • To try to repair all inconsistencies and corruption at once, use the -repair option, which includes all the region and table consistency options.

For more details about the hbck command, see Appendix C of the HBase Reference Guide.

Page generated July 8, 2016.