Case-sensitivity and the MVFS

The multiversion file system (MVFS) is a Rational® ClearCase® feature that supports dynamic views. Because it is a file system, its case-sensitivity behavior is important and needs to be reconfigured in some mixed networks. For more information, see The multiversion file system.

On Linux® and on the UNIX® system, the native file system and all Rational ClearCase components (MVFS, cleartool, and so on) are case sensitive. The MVFS always uses case-sensitive file lookup and does no case conversion.

On Windows®, the native file systems are case-preserving and not case-sensitive. Because native Windows file systems perform file lookup that is not case-sensitive, the MVFS, in its default configuration on Windows, also performs file lookup that is not case-sensitive. Windows file systems preserve case on file-creation operations. The MVFS is configured to convert file names to lowercase on Windows.

To reconfigure the MVFS on Windows to use different case-sensitivity options, use the MVFS page in the ClearCase program in Control Panel:

When you select the Case Insensitive MVFS check box (the default and recommended setting), the MVFS looks up files without regard to case. With this setting, when the MVFS writes view-private files, capitalization of file names depends on the setting of the Case Preserving check box:
- When you select the Case Preserving check box, the MVFS preserves the case of the names of new view-private files.
- When you clear the Case Preserving check box, the MVFS converts the names of new view-private files to lowercase. This is the default setting.
When you clear the Case Insensitive MVFS check box, the MVFS uses case-sensitive file lookup. With this setting, the MVFS preserves character case in the names of all files it creates.

Changes to MVFS options do not take effect until you restart your computer.

Note: Windows applications that do not specify file names with the correct case might fail in a case-sensitive MVFS.

When to use a case-preserving MVFS

In the default mode (Case Insensitive MVFS enabled, Case Preserving disabled), the MVFS converts to lowercase the names of view-private files created in a dynamic view. This behavior can interfere with the operations of tools that intentionally create files with mixed-case names. For example, if a Java™ development environment creates a file named util.JAR in an MVFS environment that is not case sensitive, it will be written as util.jar. Development tools that reference the file as util.JAR cannot find it. To correct this kind of problem, configure the MVFS to use case-preserving mode (clear the Case-Insensitive MVFS check box).