2. USAGE GUIDELINES › 2.1 TLM Component Usage Guidelines › 2.1.3 TLM Component Cost Accounting

2.1.3 TLM Component Cost Accounting

The TLM component provides a standard interface to the CA
MICS Accounting and Chargeback Option.  The database file
used for cost accounting is the Tape Data Set (TMCTMD) file.
The standard metric used for recovering the cost of tape
media storage is:

TMDDURSP - Amount of Space-Time (MByte-Hours)

This value is computed for each tape data set using the
following formula:

TMDDURSP = ((TMDBLKCT*BLKSIZE)*TIME) / 10000000

where:

TMDBLKCT is the data set block count

BLKSIZE  is the average block size in bytes

TIME     is the lesser of these values:

         o the number of hours since the data set was
           created
         o the number of hours since the data set was last
           scanned
         o the default hours if this is the first scan of
           the tape library (the default is 24 hours)

Accounting can be invoked at the DETAIL timespan where each
TLMTLD file record represents the data set on a specific
volume, or at the DAYS timespan where each TLMTLD record
represents a group of tape data sets summarized by account
codes (TLMACT1-TLMACTn), VOLGROUP, and storage management
identifiers (STORNAME, STORSTGC, STORMGTC, STORDATC).

DAYS timespan billing is encouraged because of the potential
for a very high volume of daily journal records at a typical
data center, if accounting is performed at the DETAIL
timespan level.

If complex accounting rates are used, it is important to
ensure that the granularity of observations at the DAYS
timespan level prevents tape data sets with different
charging characteristics from being summarized together.

For example, the following tape data set attributes might be
considered when deciding on a rate to charge for media
storage:

o Is the tape data set compressed?

o Is the tape data set on a virtual volume?

o Are multiple media types available, and, if so, is one more
  cost effective than another?

Even if a complex billing algorithm using variable rates is
desired, DAYS timespan billing can be used if one of the
TLMACTn account codes is set to a unique value for each
combination of data set characteristics that impact the
billing rate, in combination with a TLM VOLGROUP derivation
routine that assigns unique VOLGROUP element values to tape
volumes with different billing characteristics.

The TLMACTn account code values are populated in the TLMACRT
exit routine for each DETAIL TMCTMD file observation.  Using
one of the TLMACTn data elements to assign unique values
reflecting tape data set characteristics that influence
billing rates will result in a DAYS timespan observation for
each unique TLMACTn value.

This allows accounting algorithms to select the appropriate
rate for each group of tape data sets that share common
characteristics.

Chapter 7 describes the parameters you must specify for a
successful implementation of accounting applications.  The
Accounting and Chargeback Option Concepts and Overview Guide
and User Guide discuss various methodologies that can be used
with CA MICS TLM component billing.