The UFS also called the Berkeley Fast File System (BSD Fast File System or FFS) is a file system used by many Unix and Unix-like operating systems. Vendors of some proprietary Unix systems, such as SunOS / Solaris, System V Release 4, HP-UX, and Tru64 UNIX, and open Unix derived systems like illumos, have adopted UFS.
Linux includes a UFS implementation for binary compatibility at the read level, but Linux does not have full support for writing to UFS.