SystemManaged StorageConcepts and Components 33
• Automated disk space management
SMS has the facility to automatically reclaim space whic h is allocated to old
and unused data sets. Policiescan be defined that determine how long an
unused data set are allowed to reside on level0 volumes (active data).
Redundant or expireddata can be removed by the process of migrationto
other volumes (diskor t ape),or t he data can be deleted. Allocated but unused
space can be automaticallyreleased, which is then available for new
allocations and active datas ets.
• Improved data availability management
WithS MS,different backup requirements can be provided for data residingon
the same primary volume.Therefore, all data on a single volume can be
treated independently.The HSM component can be used to automatically
back up data.The ABARS facility can be used to group data sets into logical
components, so that the group is backedup at t he same time, allowingfor
recovery of an application.
• Simplified data movement
SMS permits the movement of data to newvolumes without the necessity for
users to amend their JCL. Because users in a DFSMS environment do not
need to specify the unit and volume which contains their data, it does not
matter to them if their data resides on a specific volume or device type.Thi s
allows the replacement of old deviceswith minimum intervention from the
user.
System determined block sizes can be utilized to automat ically reblock
sequential and partitioned data sets that can be reblocked.