Sun is working on two projects to aid file-sharing between Windows and its own OpenSolaris version of Unix.

The OpenSolaris project CIFS Server features a source code implementation of CIFS (Common Internet File System) protocol also known as Server Message Block (SMB), the standard for Windows file-sharing services, Sun said. It enables Microsoft users to store files on OpenSolaris, Sun said. This project and a related effort, CIFS client, improve the usefulness of OpenSolaris in data environments that serve NFS and CIFS clients, Sun said.

Sun recently donated server source code that implements CIFS to the OpenSolaris Project.

Windows interoperability requires a CIFS server to convince a Windows machine that it is also Windows, according to Sun. The operating system needs to support those services at a fundamental level.

Sun plans to incorporate CIFS Server in the "Indiana" release of OpenSolaris next spring and in Sun's commercial version of Solaris probably in about two years.

Conversely, CIFS client enables OpenSolaris systems to act as CIFS clients in a Microsoft environment. The client stores and retrieves files on a Microsoft CIFS system, completing file-sharing capabilities between OpenSolaris and Microsoft environments, Sun said.

A Sun senior staff engineer involved in the effort, Alan Wright, cited its importance in his blog.

"[CIFS] is the standard for Windows file-sharing services, and one of the primary goals for Solaris is to continue to improve and enhance it as a storage operating system and platform," said Wright. "Adding CIFS, to provide seamless, ubiquitous file-sharing for both CIFS (Windows, MacOS etc) clients and NFS clients is a major step towards achieving this goal. Together, with the CIFS client, which is also an OpenSolaris project, the CIFS server helps provide comprehensive, integrated native Windows interoperability on Solaris."

Supporting CIFS required changes to core OpenSolaris components including ZFS (Zettabyte File System), VFS (Virtual File System), credentials, file system utilities, and other components. Sun also has donated these changes to the OpenSolaris project.