Graceful HBase Shutdown
Graceful Shutdown causes the regions to be redistributed to other RegionServers, increasing availability during the RegionServer outage.
A graceful shutdown of an HBase RegionServer allows the regions hosted by that RegionServer to be moved to other RegionServers before stopping the RegionServer. You can perform a graceful shutdown of either an HBase RegionServer or the entire service.
Cloudera Manager waits for an interval determined by the Graceful Shutdown timeout interval, which defaults to three minutes. If the graceful stop does not succeed within this interval, the RegionServer is stopped with a SIGKILL (kill -9) signal. Recovery will be initiated on affected regions.
To increase the speed of a rolling restart of the HBase service, set the Region Mover Threads property to a higher value. This increases the number of regions that can be moved in parallel, but places additional strain on the HMaster. In most cases, Region Mover Threads should be set to 5 or lower.