16d Define storage classes.
You must perform this step at initial installation. During migration,
you must perform this step if you are adding or modifying storage
classes for object tape storage or file system sublevels.
OAM interprets the parameters used to define the storage class
in an attempt to apply the stated performance objective. The following
parameters are used by OAM as an indication of the performance objective
for the object:
- INITIAL ACCESS RESPONSE SECONDS (IARS)
- Specify a performance objective relative to the elapsed time (in
seconds) that can be tolerated before the first byte of data is made
available for an application’s request to retrieve an object.
Use from 1 to 4 characters to specify a valid value of 0 to 9999.
A value of 0 causes the object to be written to disk storage, and
a value of greater than 0 causes the object to be written to removable
media storage. Any OAM request that tries to use a storage class with
a blank value for this parameter fails.
- SUSTAINED DATA RATE (SDR)
- A subparameter of the storage class parameter that specifies which
removable media, optical or tape, is used to accept the primary copy
of the object, once the Initial Access Response Seconds parameter
determines that the object should be written to removable media. If
the SDR is greater than or equal to three, the primary copy of the
object is stored on a tape volume. If the SDR for the object is less
than three, the primary copy of the object is stored on an optical
disk volume.
- OAM SUBLEVEL (OSL)
- A subparameter of the storage class parameter to indicate what
sublevel the storage class is associated with. The valid values are
1 or 2; the default value is 1.
OAM attempts to meet the performance objective by placing the object
at a level in the storage hierarchy that comes closest to the objective.
Avoid using performance objectives that force objects to be written
directly to optical storage. Writing objects directly to optical media
without staging them through the DB2 sublevel can degrade system performance
and significantly increase the number of optical disks needed per
day, due to inefficient optical VTOC directory space utilization.
See
Table 1 for detailed information
about the effects of writing objects directly to optical media.
- AVAILABILITY
- Specify a value for this parameter (STANDARD or CONTINUOUS), even
though it is ignored for objects.