# 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. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://nag-9-s.gitbook.io/hbase/hbase-architecture/region-servers/blockcache.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.