SystemManaged StorageConcepts and Components 29
byiss uingspecific commands when manual operations are appropriate. Volumes
can be:
• Managed by SMS. In this case the Storage Group definitions controls HSM
initiated automatic functions,depending upon the appropriate Management
Class of the data set.
• Managed by HSM. These volumes are commonly known as primary or level 0.
Here each volumeis defined to HSM individually by the ADDVOLparameter
and governed accordingly.
• Owned by HSM. These incorporate migration level 1 (ML1), migration level 2
(ML2), backup,dump and aggregate volumes, and are a combination of disk
and tape. Alternate tape copies can be made of ML2 and backup tapes for
off-site storage.Also, spill volumes can be generated from backups andML2
volumes to improvetape usage efficiency.
Figure 10 shows the relationship betweenthe main components of the HSM
environment.
Figure 10. DFSMShsm Components
4.3.3.1 Space Management
On a daily basis, HSM performs automatic spacem anagement,
depending upon whether thevolume is part of an SMS Storage Group
or managed individually byHS M.Space management consists of the
followingfunctions:
•Migration
This is the process of moving eligible,inactive, cataloged data sets to
either ML1 or ML2 volumes,from pr imary volumes(Level 0). This is
DFSMShsm Environment
SMS
Storage
Groups
ML1
HSM
Primary
Volumes
Recover
Dump
ABARS
Recycle Incremental
Backup
Spill
Level0
ML2
Recycle
Recall