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External Data Managers (EDMs) are programs that manage a specific set of volumes according to internal criteria. EDMs determine retention of the volumes they control and can optionally relate to one physical file as more than one logical file.
Control-M/Tape currently supports various EDMs such as DFSMShsm, CA-Disk (formerly DMS/OS), and CA-ASM2. Each of these EDMs has its own method of naming and tracking data sets and volumes that are under its control. Control-M/Tape allows the EDM at your site to manage and expire EDM-controlled volumes, while Control-M/Tape tracks activity and supervises access of these volumes. When an EDM-controlled data set or volume is scratched, the EDM notifies Control-M/Tape through a user exit, and Control-M/Tape updates its Media Database accordingly.
EDM volumes are identified to Control-M/Tape through DO RETENTION=EDM statements in Control-M/Tape rule definitions.
Below is a sample Control-M/Tape rule that identifies EDM controlled volumes. For more information about rule definition, the Control-M/Tape User Guide.
Figure 34 Sample Control-M/Tape Rule
RULE: DFHSM LIB CTT.PROD.RULES TABLE: EDM
COMMAND ===> SCROLL===> CRSR
-------------------------------------------------------------------------------
RULE NAME DFHSM GROUP MODE PROD (Prod/Test)
OWNER M72 SEQUENCE PRIORITY CONTINUE SEARCH Y (Y/N)
DESCRIPTION
DOCMEM DFHSM DOCLIB CTT.PROD.DOC
===========================================================================
ON DATASET = HSM* And/Or/Not
===========================================================================
DO RETENTION = EDM And/Or
DO POOL = DFHSM-TAPES
DO
BMC recommends that you implement the Control-M/Tape interface to the EDM at your site while operating Control-M/Tape in Global Test mode. When Control-M/Tape is activated in Global Phased, or Global production mode, the interface to the EDM at your site must be active.
The EDM interface enables Control-M/Tape to detect when the EDM scratches a tape, so that Control-M/Tape can update the Media Database accordingly.
EDM volumes are managed at the volume level (meaning, no data set specific control is used).
If more than one data set is stored on an EDM volume, only the first data set on the volume is recorded in the Media Database.
If a data set spans more than one EDM volume, volume chaining is not recorded in the Media Database. Each volume containing part of the data set is recorded as a single (unchained) volume containing only that data set.
An EDM is allowed to create data sets only on scratch volumes, or on volumes that are already marked as EDM-controlled. If an EDM creates a data set on a scratch volume, that volume is then identified by Control-M/Tape as an EDM volume. Only an EDM is allowed to modify EDM volumes.
Information about EDM volumes listed in the Media Database can be displayed online through the Inquiry/Update screen (screen TI). For more information on the Inquiry/Update screen, see the online facilities chapter of the Control-M/Tape User Guide.
Data sets stored on EDM volumes are normally expired through a command from the EDM (meaning, not by instructions from Control-M/Tape or the other tape management system) according to the expiration mode (see Expiration Modes for EDM Volumes).
Note: EDM volumes can also be expired manually through the Control-M/Tape utility CTTMUP. For more information, see the Control-M/Tape chapter of the INCONTROL for z/OS Utilities Guide.
The EDM interface is implemented through a user exit of the EDM. This exit enables Control-M/Tape (and optionally another tape management system) to detect when data sets or volumes are marked scratch by the EDM. Sample user exits for each EDM supported by Control-M/Tape are supplied with Control-M/Tape. The user exit used for each interface and the steps needed for its implementation of interfaces for the various EDMs are described on the following pages.
Control-M/Tape messages beginning with CTTEDM describe the operations performed through this interface.
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