HP CIFS File Locking Interoperation

6.2 WINDOWS ONLY CLIENT ACCESS – NFS Mounted

File System

The diagram above shows 2 Windows clients requesting concurrent file access on the

CIFS/9000 server to a NFS mounted file system. The key issue for this configuration is that

because all Windows client access occurs via the CIFS/9000 server smbd processes, the file

access is coordinated by CIFS/9000 even thought the disk file is remote, thus providing full

file locking functionality in a Windows homogenous environment.

Mandatory Share Mode locking is fully implemented. Although no actual lock is placed upon

the disk file over the NFS mount, the client processes believe that there is, and the server

smbd processes coordinate to respect each other’s pseudo-lock. This locking scenario only

applies when a single CIFS/9000 server is supplying both client connection requests.

Byte Range locking is fully implemented. The CIFS/9000 smbd process actually calls the

UNIX fcntl to explicitly lock the byte range in UNIX with advisory byte range locks. The

UNIX byte range is then propagated to NFS, so byte range locking is interoperable with

NFS. With Windows-only concurrent access, the smbd process interprets the UNIX advisory

lock as a Windows byte range lock, which the clients honor.

Opportunistic (Oplocks) locking is fully implemented for the same reason as the Mandatory

Share Mode lock, and only applies when a single CIFS/9000 server is supplying both client

connection requests.

CIFS/9000

File

NFS

Windows

UNIX

PC-NFS

CIFS/9000

Clients