ABCs of z/OS System Programming Volume 3 - IBM Redbooks

5.16 SMS control data sets
SMS
Figure 5-16 SMS control data sets
SMS control data sets
SMS stores its class and group definitions, translated ACS routines, and system information
in three control data sets.
Source Control Data Set (SCDS)
The Source Control Data Set (SCDS) contains SMS classes, groups, and translated ACS
routines that define a single storage management policy, called an SMS configuration. You
can have several SCDSs, but only one can be used to activate the SMS configuration.
You use the SCDS to develop and test but, before activating a configuration, retain at least
one prior configuration if you need to regress to it because of error. The SCDS is never used
to manage allocations.
Active Control Data Set (ACDS)
The ACDS is the system's active copy of the current SCDS. When you activate a
configuration, SMS copies the existing configuration from the specified SCDS into the ACDS.
By using copies of the SMS classes, groups, volumes, optical libraries, optical drives, tape
libraries, and ACS routines rather than the originals, you can change the current storage
management policy without disrupting it. For example, while SMS uses the ACDS, you can:
► Create a copy of the ACDS
► Create a backup copy of an SCDS
266 ABCs of z/OS System Programming Volume 3
COMMDS
ACDS
SCDS