To use data set separation,
you must create a data set separation
profile and specify the name of the profile to the base configuration.
During allocation, SMS attempts to separate the data sets listed in
the profile.
A data set separation profile contains at least
one data set separation group. Each data set separation group specifies
whether separation is at the PCU or volume level, whether it is required
or preferred, and includes a list of data set names to be separated
from each other during allocation.
Restriction: You cannot use data set
separation when allocating non-SMS-managed data sets or with any process
that does not use SMS volume selection, such as a full-volume copy
utility (for example PPRC).
Recommendation: Use data set separation
only for a small set of mission-critical data for the following reasons:
- When separation is at the PCU level, an existing
data set might be allocated to one or more PCUs from which the current
allocation is to be separated. In this case, SMS either rejects all
volumes on the PCUs from the SMS volume preference list or places
them at a less-preferred position. Volume rejection might drastically
reduce the number of eligible volumes or result in allocation failures
if SMS rejects all volumes.
- The use of wildcard characters
in the data set
names that need to be separated from each other might drastically
reduce the number of eligible volumes or result in allocation failure
if SMS rejects all volumes.
- Data set separation can affect
system performance. See the performance
concerns listed in Factors affecting code path length.
For information about specifying the name of the data set separation
profile to the base configuration, see Specifying the DS separation profile.
The following table lists the topics that are contained in this section: