Editing IBM DevOps Code ClearCase (section)

== Builds ==

The [[networked filesystem]] provided by MVFS allows for build auditing. Builds in views that use the MVFS can monitor and record file [[I/O]] operations performed during the build process and associate each such event with the command that triggered it. This allows ClearCase to produce a [[Bill of materials|bill-of-materials]] which it calls a Configuration Record (CR) for all builds and enable [[traceability]] for either [[software configuration management]] purposes or as part of a larger [[application lifecycle management]] process. Build auditing is performed with command-line tools such as a built-in make tools (omake, clearmake) or by using the clearaudit command, which can invoke another build tool, such as Unix make (1).

The Versioned Object Base (VOB) that stores versions of file elements and directory elements also stores derived objects and metadata associated with these object types.

The bill-of-materials artifact produced as the result of build auditing is known as the ''Configuration Record''. It contains:
* The build procedure: The method (script, makefile, and so on) that invoked the build.
* Inputs: All files (and their specific versions) that were used for a particular build.
* Outputs: All [[derived object]] (DO) files (and any dependent DOs) produced as a result of the build.

The dependency information is stored in a configuration record that can be shown for each derived object. The configuration record can be used to create another view that shows all files that have been previously read during the build time. The configuration record can also be used to apply a label to the files (and versions) that were read during the build.

The MVFS allows derived objects that were built in one dynamic view to be automatically "copied" to another dynamic view that requires "exactly the same" derived object. Two derived objects are deemed to be "exactly same" if they have the same ''configuration record'' (that is, ''bill of materials''). The shareable derived objects are physically present in the VOB server, not in the views that reference them. This feature is called ''winking in'' derived objects and requires that the clearmake or omake tool is used for builds.

ClearCase dynamic views are slower than local filesystems, even with a good network infrastructure. Repeated subsequent builds may run faster, due to build avoidance that is enabled by ClearCase's [[Make (software)|make]] substitute. Because MVFS requires server access every time a file is accessed, the performance of the file system depends on server capacity.