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Converting DB2 to Systems Managed Storage 79
• Active logs and BSDS.
8.5.2 Methodology
8.5.2.1 Conversion Window
Decide when each type of data is available for conversion. During a normal
processing cycle, some data sets will be deleted and reallocated, providing the
opportunity for SMS management. Online data must be converted when those
services are unavailable (down time). This is the most difficult to schedule, and
requires precise planning.
8.5.2.2 Data Movement
Each disk device is either SMS managed or not. A data set is considered SMS
managed when:
• It has a valid Storage Class.
• It resides on a volume in an SMS Storage Group, or has been migrated by
DFSMShsm.
Data sets can be:
• Converted with movement
• Converted in place
Converted with Movement
This is achieved by using a space management function such as DFSMSdss
COPY, DFSMSdss DUMP/RESTORE or DFSMShsm. This method is applicable if
the data is application owned. However, consideration must be given to the
number of spare disk devices required, while this method is in progress. Also,
consider using this approach if the disk devices being used are positioned with
storage controls of varying performance (caching). An advantage with this
method is allowing data to be allocated using volume thresholds set for each
Storage Group, thus allowing space management to operate.
For tablespaces, the DB2 utility REORG can be used to automatically convert
with data movement if the tablespace is DB2 defined. If it user defined, then a
IDCAMS DELETE/DEFINE CLUSTER must be executed between the REORG
phases.
Converted in Place
This is achieved by using DFSMSdss CONVERTV function. This approach
requires exclusive use of the data sets residing on the disk device. If data sets
are already positioned in pools of volumes, this may be an appropriate method to
use (tablespaces are likely to be grouped this way). Be warned, if the volume and
data sets do not meet all SMS requirements, DFSMSdss will set the volume's
physical status to initial. This status will allow data sets be accessed, but not
extended. New allocations on the volume are prevented. If all requirements are
met, DFSMSdss will set the volume status to CONVERTED.
8.5.2.3 Tailor Online Conversion
Many installations have data sets that are open and active most of the time.
Staging a conversion into smaller manageable portions of data provides safer
implementation results.