The NameNode cache configuration parameters are defined in hdfs-site.xml
file. The NameNode cache configuration parameters are:
dfs.resolvingcache.enabled: (true/false) Enable/Disables the cache for the NameNode.
dfs.resolvingcache.type: Each NameNode caches the inodes metadata in a local cache for quick path resolution. We support different implementations for the cache, i.e., INodeMemcache, PathMemcache, OptimalMemcache and InMemory.
- INodeMemcache: stores individual inodes in Memcached.
- PathMemcache: is a course grain cache where entire file path (key) along with its associated inodes objects are stored in the Memcached.
- OptimalMemcache: combines INodeMemcache and PathMemcache.
- InMemory: Same as INodeMemcache but instead of using Memcached it uses an inmemory LRU ConcurrentLinkedHashMap. We recommend InMemory cache as it yields higher throughput.
For INodeMemcache/PathMemcache/OptimalMemcache following configurations parameters must be set.
The InMemory cache specific configurations are: