> For the complete documentation index, see [llms.txt](https://nag-9-s.gitbook.io/hbase/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nag-9-s.gitbook.io/hbase/hbase-architecture/region-servers/blockcache.md).

# 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.