Registering External (Foreign) Tapes

This chapter includes the following topics:

Overview

Data centers use various methods to track the storage location and external identification of removable media. Some data centers use a volume serial number to refer to a specific volume. Other data centers refer to tapes by slot IDs (corresponding to physical storage slots) or by volume groups (corresponding to application, and so on.)

Control-M/Tape identifies volumes in its Media Database by volume serial number (volser). These volsers are usually physically recorded in a volume’s internal label when the volume is initialized. Volsers should always be unique within a single site.

Many data centers regularly receive volumes from other sites. In some cases, these volumes may have the same volsers as volumes already in use at the data center. This creates a duplicate volser situation. The mechanism used by Control-M/Tape to handle duplicate volsers is described in under Duplicate Volser Considerations.

Control-M/Tape enables users to check in external volumes, either through the Online facility, or through an Automatic Check-In process. These volumes are marked as External Volumes in the Media Database. They are processed through the same management, control, and protection procedures as local volumes. External volumes are considered a separate tape pool (call EXTERNAL). The Control-M/Tape Retention Management utility (CTTRTM) lists the EXTERNAL pool separately in its Scratch report. This makes it easier to track expiration of external volumes.

When an external volume reaches its expiration date, it can either be deleted from the Media Database or it can be handled like regular volumes, which are marked SCRATCH but remain in the Media Database.

Traditional Handling of External Tapes

Most tape management systems ignore "external" volumes. When a data center receives volumes from other sites, these systems neither manage them (in terms of their usage or expiration) nor control their physical storage location within the data center. External volumes are not protected from being overwritten or from being used as SCRATCH volumes by these systems.

Some tape management systems allow external volumes to be manually checked in. However, even these systems do not properly protect external volumes (for example, by preventing files from being overwritten).

Security products used by most tape management systems for resident media are bypassed for external volumes. In these systems, external volumes are specified in job statements through the JCL parameter EXPDT=98000. This parameter indicates that the tape management system should ignore the action that follows and not to perform security checks on the volume. When volume checking is bypassed for external tapes, there is no way to prevent them from being overwritten or used as SCRATCH volumes..

Control-M/Tape Handling of External Tapes

The Control-M/Tape Check-in facility registers external tapes in the Media Database so that they can be managed, controlled, and protected in the same manner as local (resident) tapes. This process can be activated automatically when a tape is mounted, or manually through the online Check-In facility (Screen TC).

Automatic Check-In Process

The DYNVOL Control-M/Tape installation parameter indicates how automatic check-in of volumes should be performed. When automatic check-in is activated, if a job attempts to access a volume that is not defined in the Media Database, Control-M/Tape checks the value specified for the DYNVOL parameter and proceeds accordingly. Valid values for the DYNVOL parameter are:

Table 25 Values for the DYNVOL Parameter

Value

Description

P

A message is displayed prompting the operator to specify if a volume record should be added to the Media Database.

E

A volume record is added to the Media Database and the volume is marked as an External Volume. No message is sent to the operator.

Y

A volume record is added to the Media Database. The volume is not marked as an external volume. No message is sent to the operator.

I

The volume is ignored. Processing of the job continues without the intervention of Control-M/Tape. No information is recorded in the Media Database regarding the volume or the data sets contained in that volume. (This value produces a result similar to the JCL parameter EXPDT=98000.)

N

The volume definition is not added to the Media Database and the job abends for specific tape requests, or the tape is rejected for nonspecific (scratch) requests.

Some tape management systems allow external volumes to be manually checked in. However, even these systems do not properly protect external volumes (for example, by preventing files from being overwritten). When a volume definition is added to the Media Database during the automatic check-in process, retention information is obtained from the corresponding JCL statement, a default Control-M/Tape rule definition ($DEFAULT), or the default retention period specified through the DEFEXPDT Control-M/Tape installation parameter.

External Volume Check-In Facility

The Control-M/Tape External Volume Check-In screen, shown in Figure 42, allows definition of external volumes for addition to the Control-M/Tape Media Database.

Figure 42 External Volume Check-In Screen

Copy 
------------- CONTROL-M/TAPE EXTERNAL VOLUME CHECK-IN SCREEN  -------------(TC)
COMMAND ===>                                                                  
+-----------------------------------------------------------------------------+
| VOLSER      123456                      Locally assigned VOLSER             |
| SL-NAME     123456                      Internal volume label               |
| MEDIA TYPE  CART                        Type of media                       |
| LABEL TYPE  SL                          Type of label (SL/NL/NSL/AL)        |
| PRINT LABEL N                           (Y/N) Print gummed label?           |
| MVS CATALOG Y                           (Y/N) Catalog datasets?             |
| DEL EXPIRED                             (Y/N) Delete when expired?          |
| RETENTION   DAYS            0090        DAYs/DATe/Permanent/Catalog/Rules   |
| ADDITIONAL INFORMATION -----------------------------------------------------|
| DESCRIPTION INPUT DATASET               USER FIELD                          |
| VENDOR                                  OWNER                               |
| EXTERNAL VOLUME DATASET LIST -----------------------------------------------|
| DATASET# 01 DSN.INPUT.DATASET                                               |
| DATASET# 02                                                                 |
| DATASET# 03                                                                 |
| DATASET# 04                                                                 |
| DATASET# 05                                                                 |
+-----------------------------------------------------------------------------+

During installation, a prefix for external volumes can be specified through the EXTRNVOL parameter. When each external volume is checked in, it is assigned a unique volser that is comprised of this prefix and a serial number. External volsers can then optionally be used to sort external volumes (for example, they may be arranged in slots whose numbers correspond to the serial numbers in the assigned volsers).

The Control-M/Tape External Volume Check-In screen contains fields specifying

  • unique volume serial number (VOLSER)

  • actual internal volume name (SL-NAME)

  • media type

  • label type

  • retention period

  • data set list

  • additional volume list (for multivolume data sets)

  • whether data sets in the data set list should be cataloged

If specific data sets are listed in the External Volume Check-in screen, data set records are created (in the Media Database) for these data sets when the volume is checked in. Retention period information is essential for retention management of external volumes. The DEL EXPIRED field specifies if a volume record is kept in the Media Database after the volume expires. If no value is specified for the DEL EXPIRED field, the external volume is kept in the Media Database after expiration.

For a more detailed description of the External Volume Check-In screen, see the online facilities chapter of the Control-M/Tape User Guide.

Duplicate Volser Considerations

External volumes checked in to Control-M/Tape sometimes have the same volser as a volume already in the Control-M/Tape Media Database. This is problematic because the volser must be a unique identifier of a volume in the Media Database. To solve this problem, Control-M/Tape uses two fields, VOLSER and SL-NAME (Standard Label Name) to identify volumes in the Media Database.

Table 26 VOLSER and SL-NAME

Volume Identifiers

Description

VOLSER

The VOLSER field is used to enter the logical volser in the Media Database. This is the unique volser assigned to the checked-in volume. When a volume is checked in, the value in the VOLSER field is used to identify and access the volume (for example, in JCL references, job statements, references in the MVS catalog, and mount messages).

A logical volser can be automatically generated with the prefix specified in the EXTRNVOL installation parameter, or it can be specified manually in the External Volume Check-In screen. Assigning a unique logical volser does not affect the physical (internal) label on the volume in any way.

SL-NAME

The physical volser (Standard Label name) is stored in the SL-NAME field of a volume record. For local volumes, the SL-NAME and VOLSER are the same.

For external volumes, the SL-NAME is used to reconcile the discrepancy between the requested volser, and the mounted volume’s standard label, when they do not match.

When an external volume is checked in, a new logical volser is used to identify the volume. In addition, the original volser (on the volume’s internal label) is stored in the SL-NAME field.

When a job requests a specific volume through a JCL statement, the operating system checks that the volser on the volume’s internal label matches the requested volser.

If the requested volume and the internal label do not match, the operating system would normally reject the tape. However, when a volume is defined to Control-M/Tape with different values in the VOLSER field and the internal label, Control-M/Tape intervenes in the operating system processing. If the value in the SL-NAME field matches the volser in the internal label, Control-M/Tape forces the operating system to accept the volume.

The special handling described above is supported only when tapes are accessed through a READ function. If a tape with a duplicate name is opened for WRITE access, the internal label of the tape (volume) is changed so that it matches the external name of the volume.

An external volume with an internal standard label of 111111 is delivered to the data center. The tape librarian checks in the tape and finds that there is already an existing volume with this volser in the Media Database. A unique value, NEW111, is assigned to the volume and entered in the VOLSER field. The original volser value (111111) is entered in the SL-NAME field.

When the volume is requested for processing, the JCL statement includes the parameter VOL=SER=NEW111. The operator mounts volume NEW111. Normally, the operating system would reject the mounted volume since the internal label (111111) does not match the requested volser (NEW111). However, Control-M/Tape performs its own validation checking routine. Control-M/Tape determines that the value in the SL-NAME field (111111) matches the internal label of the mounted tape. Control-M/Tape forces the operating system to accept the volume for processing.

Every Monday morning a tape is delivered from the social security office with the same physical standard label (SS0001). The tape librarian checks in the tape using the External Volume Check-In screen and an automatically generated volser, as shown in Figure 43.

Figure 43 Check-in Screen

Copy 
------------  CONTROL-M/TAPE EXTERNAL VOLUME CHECK-IN SCREEN  -------------(TC)
COMMAND ===>                                                                  
+-----------------------------------------------------------------------------+
| VOLSER      EXT045                      Locally assigned VOLSER             |
| SL-NAME     SS0001     +--------------------------------------+             |
| MEDIA TYPE  3490       |   PLEASE CONFIRM ADDING OF           |             |
| LABEL TYPE  SL         |   VOLUME EXT045 TO THE MDB Y (Y/N)   |L/AL)        |
| PRINT LABEL N          +--------------------------------------+l?           |
| MVS CATALOG Y                           (Y/N) Catalog datasets?             |
| DEL EXPIRED                             (Y/N) Delete when expired?          |
| RETENTION   DAYS            0090        DAYs/DATe/Permanent/Catalog/Rules   |
| ADDITIONAL INFORMATION -----------------------------------------------------|
| DESCRIPTION SOCIAL SECURITY TAPE        USER FIELD                          |
| VENDOR                                  OWNER                               |
| EXTERNAL VOLUME DATASET LIST -----------------------------------------------|
| DATASET# 01 SS.INPUT.DATASET.D021298                                        |
| DATASET# 02                                                                 |
| DATASET# 03                                                                 |
| DATASET# 04                                                                 |
| DATASET# 05                                                                 |
+-----------------------------------------------------------------------------+

A gummed label with the new logical volser (EXT045) is applied externally to the tape.

When online inquiries are made about the tape, the original volser (meaning, the SL-NAME) is entered in the Inquire/Update entry panel.

Figure 44 Inquire/Update Entry Panel

Copy 
-------------  CONTROL-M/TAPE  -  INQUIRE/UPDATE ENTRY PANEL  -------------(TI)
COMMAND ==>                                                                   
SELECT BY:                                                                    
   MEDIA        ===>                        Media type                        
   DSNAME       ===>                                                          
   VOLSER       ===>          TO            Volser/Mask                       
   SL-NAME      ===> SS0001   TO            SL-Name/Mask                      
   POOL         ===>                        Pool name/Mask                    
   LOCATION     ===>                        Location name/Mask                
                                                                              
SELECT BY DATE:                                                               
   CREATE FROM  ===>          TO            Creation date range               
   EXPIRE FROM  ===>          TO            Expiration date range             
   ACCESS FROM  ===>          TO            Last access date range            
                                                                              
SELECT BY STATUS:                                                             
   ACTIVE       ===> Y                      VAULTED only ===> N               
   SCRATCH      ===> Y                      EXTERNAL     ===> Y               
   EDM CONTROL  ===> Y                      ATL/VTS only ===> N               
                                            WORM only    ===> N                                                                             
DISPLAY OPTIONS:                                                              
   DISPLAY TYPE ===> V                      RECORD TYPE  ===>                 

All volumes with an SL-NAME of SS0001 are retrieved from the Media Database.

Figure 45 Retrieval List

Copy 
DATABASE LIST < V / V  > --------------------------------------------------(TI)
COMMAND ===>                                                    SCROLL===> CRSR
O VOLSER    VOLSEQ MEDIA      RETENTION  L-ACCESS  FILES LOCATION ---STATUS----
  EXT015           3400       01/08/01              0001 MAINLIB  Ext-Active  
  EXT021           3400       01/15/01              0001 MAINLIB  Ext-Active  
  EXT027           3400       01/22/01              0001 MAINLIB  Ext-Active  
  EXT032           3400       01/29/01              0001 MAINLIB  Ext-Active  
  EXT037           3400       02/05/01              0001 MAINLIB  Ext-Active  
  EXT045           3400       02/12/01              0001 MAINLIB  Ext-Active  
====== >>>>>>>>>>>>>>>   NO MORE ENTRIES IN THE LIST     <<<<<<<<<<<<<<< ======

Retention of External Volumes

When checking in external volumes using the External Volume Check-In screen, the retention period is entered on the screen in the RETENTION field.

Valid retention values are:

Table 27 External Volume Check-in Values

Value

Description

DAYS

Volume is retained for a specified number of days.

DATE

Volume is retained until a specified date.

CATALOG

Volume is retained as long as any of its data sets are maintained by the MVS catalog.

PERMANENT

Volume is retained indefinitely.

RULES

Volume is retained as long as at least one of its data sets is retained. The retention and vault pattern for each data set listed in the EXTERNAL VOLUME DATASET LIST (of screen TC) is determined according to Control-M/Tape rules. However, Control-M/Tape must be active to use these rules.

After Expiration

When an external volume is due for expiration, it can either be physically deleted from the Media Database (and returned to its place of origin), or it can remain in the Media Database and be handled like a regular volume (meaning, it can be assigned a status of EXT-SCRATCH and can then be used as a scratch tape). Information about expired external volumes marked EXT-SCRATCH is saved in the Media Database, and can be retrieved as needed.

The DEL EXPIRED field (specified during check-in of an external volume) indicates if a volume should be physically deleted from the Media Database upon expiration. The default is not to delete the volume. Option D (Delete) of the Inquire/Update Screen can be used to delete an external volume from the Media Database after it has expired. Only volumes with a status of EXT-SCRATCH can be deleted from the Media Database with option D.

Records describing external volumes checked in through the Automatic Check-In facility are automatically deleted from the Media Database when the relevant volumes are expired. The DEL EXPIRED field is irrelevant for these volumes. If you want to keep volumes with a status of EXT-SCRATCH in the Media Database, the labels of these volumes must be modified so that the volser and SL-name match. Label modification can be performed through the CTTTPI utility. Once the volumes are relabeled, they are treated as local volumes.

Implementation Steps

You can use the following step to implement Control-M/Tape support for external volumes at your site:

Step 1 – Activate the Automatic Check-In Process

  1. Specify (E,E) for the DYNVOL Control-M/Tape parameter. This value causes volume records for external volumes that are checked in to be automatically added to the Media Database. It also instructs Control-M/Tape to mark the volume being checked in as External (in the volume record in the Media Database).

  2. Specify Y for the DYNDS Control-M/Tape parameter to automatically add the data set records to the Media Database for the data sets listed in the External Volume Check-In screen.

    Specifying Y for the DYNDS and DYNVOL Control-M/Tape installation parameters causes volumes and data sets to be automatically defined any time an accessed volume or data set is not described in the Media Database. Therefore, these parameters do not only affect external volumes.

Step 2 – Activate Automatic Volser Generation

  1. Specify a volser prefix in the EXTRNVOL Control-M/Tape installation parameter to enable automatic generation of volsers in the External Volume Check-In screen.

  2. Estimate the number of external tapes the data center receives and retains to determine the length of the prefix that should be specified (for example, a three character prefix allows a range of up to 999 volumes).

  3. Choose a naming convention for external volumes if the automatic generation of volsers is not activated (that is, no value is specified for the EXTRNVOL parameter).