BlockCache

• A block cache instance is created at the time of the region server startup and it can have

  an implementation of LruBlockCache, SlabCache, or BucketCache.

• The block cache

  also supports multilevel caching; that is, a block cache might have frst-level cache,

  L1, as LruBlockCache and second-level cache, L2, as SlabCache or BucketCache.

• All these cache implementations have their own way of managing the memory; for

  example, LruBlockCache is like a data structure and resides on the JVM heap whereas

  the other two types of implementation also use memory outside of the JVM heap.