hbase-2 needs to defend against hbck operations

As of HBase version 2.0, the hbck tool is significantly changed. In general, all Read-Only options are supported and can be be used safely. Most -fix/ -repair options are NOT supported. Please see usage below for details on which options are not supported: Usage: fsck [opts] {only tables}  where [opts] are:    -help Display help options (this)    -details Display full report of all regions.    -timelag <timeInSeconds> Process only regions that have not experienced any metadata updates in the last <timeInSeconds> seconds.    -sleepBeforeRerun <timeInSeconds> Sleep this many seconds before checking if the fix worked if run with -fix    -summary Print only summary of the tables and status.    -metaonly Only check the state of the hbase:meta table.    -sidelineDir <hdfs://> HDFS path to backup existing meta.    -boundaries Verify that regions boundaries are the same between META and store files.    -exclusive Abort if another hbck is exclusive or fixing.   Datafile Repair options: (expert features, use with caution!)    -checkCorruptHFiles Check all Hfiles by opening them to make sure they are valid    -sidelineCorruptHFiles Quarantine corrupted HFiles. implies -checkCorruptHFiles  Replication options    -fixReplication Deletes replication queues for removed peers   Metadata Repair options supported as of version 2.0: (expert features, use with caution!)    -fixVersionFile Try to fix missing hbase.version file in hdfs.    -fixReferenceFiles Try to offline lingering reference store files    -fixHFileLinks Try to offline lingering HFileLinks    -noHdfsChecking Don't load/check region info from HDFS. Assumes hbase:meta region info is good. Won't check/fix any HDFS issue, e.g. hole, orphan, or overlap    -ignorePreCheckPermission ignore filesystem permission pre-check NOTE: Following options are NOT supported as of HBase version 2.0+.   UNSUPPORTED Metadata Repair options: (expert features, use with caution!)    -fix Try to fix region assignments. This is for backwards compatiblity    -fixAssignments Try to fix region assignments. Replaces the old -fix    -fixMeta Try to fix meta problems. This assumes HDFS region info is good.    -fixHdfsHoles Try to fix region holes in hdfs.    -fixHdfsOrphans Try to fix region dirs with no .regioninfo file in hdfs    -fixTableOrphans Try to fix table dirs with no .tableinfo file in hdfs (online mode only)    -fixHdfsOverlaps Try to fix region overlaps in hdfs.    -maxMerge <n> When fixing region overlaps, allow at most <n> regions to merge. (n=5 by default)    -sidelineBigOverlaps When fixing region overlaps, allow to sideline big overlaps    -maxOverlapsToSideline <n> When fixing region overlaps, allow at most <n> regions to sideline per group. (n=2 by default)    -fixSplitParents Try to force offline split parents to be online.    -removeParents Try to offline and sideline lingering parents and keep daughter regions.    -fixEmptyMetaCells Try to fix hbase:meta entries not referencing any region (empty REGIONINFO_QUALIFIER rows)   UNSUPPORTED Metadata Repair shortcuts    -repair Shortcut for -fixAssignments -fixMeta -fixHdfsHoles -fixHdfsOrphans -fixHdfsOverlaps -fixVersionFile -sidelineBigOverlaps -fixReferenceFiles-fixHFileLinks    -repairHoles Shortcut for -fixAssignments -fixMeta -fixHdfsHoles