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

The second-newest version is treated as though it had been created on the same day as the
newest backup version. Therefore, the second-newest version (newest EXTRA backup copy)
is not expired until the number of retention days specified by the RETAINDAYS value or the
number of days specified in RETAIN DAYS EXTRA BACKUPS attribute in the management
class have passed since the creation of the newest backup version. (The management class
value is only used if RETAINDAYS was not specified for the version).
EXPIREBV processing and RETAINDAYS
For EXPIREBV processing, the RETAINDAYS value takes precedence over all existing
criteria when expiring active and retained backup copies for SMS data sets and non-SMS
data sets. EXPIREBV needs to be run to delete backup versions with RETAINDAYS values
that have been met.
The EXPIREBV command is used to delete unwanted backup and expired ABARS versions of
SMS-managed and non-SMS-managed data sets from DFSMShsm-owned storage. The
optional parameters of the EXPIREBV command determine the deletion of the backup versions
of non-SMS-managed data sets. The management class attributes determine the deletion of
backup versions of SMS-managed data sets. The management class fields Retain Extra
Versions and Retain Only Version determine which ABARS versions or incremental backup
versions are deleted. The RETAINDAYS parameter specified on the data set backup request
determines how long a data set backup copy is kept for both SMS-managed and
non-SMS-managed data sets.
BACKDS command
The BACKDS command creates a backup version of a specific data set. When you enter the
BACKDS command, DFSMShsm does not check whether the data set has changed or has met
the requirement for frequency of backup. When DFSMShsm processes a BACKDS
command, it stores the backup version on either tape or the ML1 volume with the most
available space.
With z/OS V1R11, the RETAINDAYS keyword is an optional parameter on the BACKDS
command specifying a number of days to retain a specific backup copy of a data set. If you
specify RETAINDAYS, number of retain days is a required parameter that specifies a
minimum number of days (0-50000) that DFSMShsm retains the backup copy. If you specify
99999, the data set backup version never expires. Any value greater than 50000 (and other
than 99999) causes a failure with an ARC1605I error message. A retain days value of 0
indicates that:
► The backup version might expire within the same day that it was created if EXPIREBV
processing takes place or when the next backup version is created,
► The backup version is kept as an active copy before roll-off occurs,
► The backup version is not managed as a retained copy.
226 ABCs of z/OS System Programming Volume 3