PFS  is the parallel file system on the Intel Paragon. In addition to a Unix-like read/write interface, PFS also supports several file-pointer modes that specify the semantics of concurrent file access. The Unix-like interface and the M_UNIX and M_ASYNC modes are straightforward to implement on top of ADIO. M_LOG mode can be implemented by emulating shared file pointers on top of ADIO. M_SYNC, M_RECORD, and M_GLOBAL modes can be implemented by using collective operations.