What is Infinispan's GridFileSystem?
Infinispan's GridFileSystem is a new, experimental API that exposes an Infinispan-backed data grid as a file system. This API is available in Infinispan 4.1.0 (from 4.1.0.ALPHA2 onwards).  Specifically, the API works as an extension to the JDK's File, InputStream and OutputStream classes: specifically, GridFile, GridInputStream and GridOutputStream. A helper class, GridFilesystem, is also included.  Essentially, the GridFilesystem is backed by 2 Infinispan caches - one for metadata (typically replicated) and one for the actual data (typically distributed). The former is replicated so that each node has metadata information locally and would not need to make RPC calls to list files, etc. The latter is distributed since this is where the bulk of storage space is used up, and a scalable mechanism is needed here. Files themselves are chunked and each chunk is stored as a cache entry, as a byte array.