Overview of feature levels

Feature levels allow different replica hosts in a VOB family to run different versions of DevOps Code ClearCase®.

Later versions of DevOps Code ClearCase may introduce features that are incompatible with earlier versions, but you may not be able to upgrade all replica hosts at the same time. Feature level control enables you to upgrade replica hosts at different times and to prevent developers at sites running later versions of DevOps Code ClearCase from using new features that are not meaningful to replicas on hosts running earlier versions.

Each version of DevOps Code ClearCase, each VOB family, and each replica has a feature level. Thus, each VOB family has one family feature level and possibly several replica feature levels. The family feature level determines which DevOps Code ClearCase features can be used by all of the replicas in the family. The following constraints are enforced:
  • The replica feature level is less than or equal to the feature level of the version of DevOps Code ClearCase installed on the replica’s server host.

    Different replicas on the same server host can have different feature levels.

  • The family feature level is less than or equal to the lowest replica feature level found among replicas in the VOB family. For example:
    • In a VOB family, two replicas are at feature level 3 and the third replica is at feature level 4. The VOB family feature level must be equal to or less than 3.
    • In another VOB family, all replicas in the family are at feature level 3. The VOB family feature level must be equal to or less than 3.
The general procedure for raising a family's feature level is as follows:
  1. Install the new version of DevOps Code ClearCase on the server hosts of replicas in the VOB family.
  2. Raise the feature level of each replica in the VOB family. For details, see Raising the replica feature level.
  3. Raise the feature level of the VOB family. For details, see Raising the VOB family feature level.

You can complete these steps incrementally and over a period of days or weeks, if necessary. Variations are possible; for example, if a VOB family has replicas R1 and R2 on servers S1 and S2, respectively, you can install a new version of DevOps Code ClearCase on S1 and raise R1's replica feature level before installing the new version on S2. However, you cannot raise the feature level of a VOB family until you have raised all replicas in that family to the new feature level.

For information about feature level values, the features that they enable, and the releases with which they are associated, see technote 73065.