The Availability field is used to specify whether data set access
should continue in the event of a single device failure. Storage classes
with a blank Availability field default to NOPREF.
- CONTINUOUS
- Specify an availability of CONTINUOUS if you do not want a device
failure to affect processing. Only duplexed and RAID volumes are eligible
for this setting.
If CONTINUOUS availability is specified, data
is placed on a device that can guarantee that it can still access
the data in the event of a single device failure. This option can
be met by
- A dual copy volume
- An array DASD
- PREFERRED
- Array DASD volumes are preferred
over nonduplexed volumes. Dual Copy volumes are not candidates for
selection.
- STANDARD
- If data sets do not require such a high level of availability,
specify STANDARD availability, which represents normal storage needs.
Specify an availability of STANDARD to cause processing of a data
set to stop after a device failure. Simplex volumes are preferred
over array DASD. SMS selects only volumes that are not dual
copy. This attribute does not apply to objects. Array DASD are acceptable
candidates for both STANDARD and CONTINUOUS availability requests.
- NOPREF
- Simplex and array DASD are equally considered for volume selection.
NOPREF is the default. Dual copy volumes are not candidates for selection.
z/OS DFSMSdfp Storage Administration
Copyright IBM Corporation 1990, 2014