A SCALABLE RECORD LOCKING SCHEME FOR PARALLEL FILE ACCESS

File systems being used as standard software in today's computer syste ms have to deal with access conflicts when several processes request I /O operations to the same file. There have to be coordination mechanis ms for resolving such conflicts according to the prescriptions of the POSIX standard. Access coordination is usually implemented by executin g file operations by one process exclusively, sacrificing scalability of multiple concurrent accesses in multicomputers. To resolve this pro blem, we propose a scalable coordination scheme which avoids sequentia lization of accesses by locking only parts of the file (i.e. arbitrary records). It allows several processes to operate on the same file tru ly in parallel, while POSIX semantics is retained. Scalability is achi eved by employing scalable shared memory access mechanisms and scalabl e elementary locks. The locking scheme has successfully been tested wi thin an experimental file system implementation.