MOB storage cache properties
Opening a MOB file places corresponding HFile-formatted data in active memory. Too many open MOB files can cause a RegionServer to exceed the memory capacity and cause performance degradation. To minimize the possibility of this issue arising on a RegionServer, you might need to tune the MOB file reader cache to an appropriate size so that HBase scales appropriately.
The MOB file reader cache is a least recently used (LRU) cache that keeps only the most recently used MOB files open. Refer to the MOB Cache Properties table for variables that can be tuned in the cache. MOB file reader cache configuration is specific to each RegionServer, so assess and change, if needed, each RegionServer individually. You can use either one of the two following methods.