42 Storage Management with DB2 for OS/390
DFSMShsm's automatic backup services,suppor ted byc oncurrentcopy, to help
with pointof consistency backups.
It is not advisableto use HSM to manage most production databases. Therefore,
use a NOMIGRATEManagement Class for this type of data. This prevents HSM
space and availabilitym anagement from operating. Specifically,AUTO BACKUP
is set to NO so that HSM does not back up the data set,A DMIN OR USER
COMMAND BACKUP is set to NONE to preventmanual backup, and expiration
attributes are sett oNOLIMIT to prevent data set deletion.
Although production database data does receive automaticbackup ser vice,
DFSMSdss can be set to run concurrent copy for productiondat abases.
ACCESSIBILITYmaybe set to CONTINUOUS for Storage Classes assigned to
production databases toensure that the data set is allocated behind a storage
control with concurrent copy support.
Testingor end user databases that have less critical availability requirements can
benefit from system management using HSM. Additionally,selected data types
for productionsy stemscould also be effectivelymanaged using HSM.
For DB2 systems, iti s possibleto manage archive logs and image copies with
HSM. These data setscan be retained on primary devices for a short period of
time, and then migrateddirectly to tape (ML2).
HSM uses the same ML2 tape until it is full.T herefore,unless another
mechanism is used, to avoid placingc onsecutivearchive logs on the same ML2
tape, ensurethat the storage administrator defines the HSM parameter
SETSYS(PARTIALTAPE(MARKFULL),so it uses a new ML2 tape each time
space management is executed.
Requirements should be agreed upon by the storage administratorand t he DBA.
Table10 on page 42 displays a list of attributes for consideration.
Table10. Management Class Attributes
ATTRIBUTE COMMENT
Spacemanagement -Release unused space in the data set (applies to
non-VSAMonly).
Expiration -Delete data set after a number of days or a date.
-Delete after a number of days of non usage.
-Use of Retention or Expiration periods.
Migration -What method a data set can migrate (Command
orautomatically,or both).
-Number of days non-usage on level 0 volumes
before migration com mences.
-Number of days non-usage on level 1 volumes
before migration com mences.