In the future, the VxFS version on a particular system may need to be downgraded from a newer VxFS release to VxFS 5.0. This may happen when a file system is migrated from one operating system using the newer VxFS release to another using the VxFS 5.0 release. If the FCL file created by this future VxFS version is Version 3 or 4, it can then be used as is by the VxFS 5.0 installation. Changes will continue to be tracked in the same FCL.

However, if the FCL version is higher than 4, then the FCL can not be activated and the calls to the API functions fail. In this case, the existing FCL file needs to be removed using fcladm rm and re-activated with FCL Version 3 or 4.