Controlling backup environment options
In addition to general options that can apply to any RUV job step, you can use the SET command and the SET DEFAULT command to control backup environment options. These options tell RUV how to handle backup-related concerns, such as which backup methods you want to enable and how long to keep backup registration records in the repository.
This topic contains the following information:
Backup environment options
You can use the following keywords on SET and SET DEFAULT commands to control backup environment options:
BACKUP_METHOD
Use the BACKUP_METHOD keyword to enable or disable the use of the various backup methods that RUV supports, including Backup-While-Open (BWO) backups, Instant Snapshot copies, RBA0 backups, and external backups. RUV backups are always enabled. The creation of SMS backups and external backups is not affected by this keyword; however, this keyword does control RUV use of these types of backups during restore and recovery processing. For more information, see Using-the-BACKUP_METHOD-keyword.
BACKUP_CHANGED_ONLY and INCREMENTAL_BACKUP_SUPPORT
RUV works with the VTOC flag that indicates whether the file has been changed since the last backup.
You can use the INCREMENTAL_BACKUP_SUPPORT keyword to control whether RUV performs a requested backup for an individual file if the data set has not been changed since the last backup and also to control whether RUV resets the flag at the end of the backup process to indicate that a backup has been performed. For more information, see Using-the-INCREMENTAL_BACKUP_SUPPORT-keyword.
If you use groups, you can use the BACKUP_CHANGED_ONLY keyword on the SET or SET DEFAULT command to control whether RUV performs requested backups of all files in the group or only the files that have changed since the last backup. For more information, see Using-the-BACKUP_CHANGED_ONLY-keyword.
READER_TASKS
Use the READER_TASKS keyword on the SET DEFAULT or SET command to control the maximum number of reader tasks (TCBs) that RUV can attempt to attach for reading input files. This option is used in situations where RUV can process input files simultaneously and you want to limit the number of input tape drives. The resources that you make available with this keyword can also prevent multitasking of the reader process. For more information, see Using-the-READER_TASKS-keyword.
DAYS or CYCLES
Use the DAYS or CYCLES keyword to control the retention period for backup information in the repository. The repository purge process removes backup registration records automatically based on the DAYS or CYCLES value. These keywords have no effect on the backup process, but they do control how long backup registration records are kept.
You can specify DAYS or CYCLES on ADD VSAM_FILE, ADD SEQ_FILE, UPDATE SEQ_FILE, and UPDATE VSAM_FILE commands as well as on SET and SET DEFAULT commands. For more information, see Purging-repository-records, Using-the-CYCLES-keyword, and Using-the-DAYS-keyword.
Default and override values
As you are implementing RUV in your backup environment, evaluate the default values of the backup environment options to ensure that they are suitable for the methods and strategies that you have chosen and for the majority of the backup job steps in your environment. To determine which default values are in effect in your environment, use the REPORT DEFAULT command, as described in Creating-reports.
If one or more default values are not appropriate, use the SET DEFAULT command to change them as described in Setting-default-and-override-environment-options.
As you are setting up a new backup job step, evaluate whether the default values for backup environment options are appropriate for the job step. If they are not, you can set override values for the options by coding the SET command in the SYSIN control statement data set in the backup job step as described in Setting-default-and-override-environment-options.
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