13.2.3.2. Accounting Interv als and Charges
The time between accounting runs and the charging policy for space usage should be developed after
consulting the accounting requirements. The following are some guidelines to consider:
•Accounting should be run at a regular intervals, such as once per month.
•An accounting run may take several minutes, and the storage system will probably be active
during the run. The resource usage reported for each user will reflect the resources used by that
user at the point when the accounting run encounters that user. This is why accounti ng represents
a blurred snapshot instead of a snapshot at a single point in time.
•Certain accounting information is kept in cache for several minutes after it has changed. For this
reason, changes to a user’s accounting data may not appear in an accounting report until this
period of time has elapsed. Those changes which are still in cache when accounting runs will not
appear on the current accounting report, but will appear on the next accounting report.
•The number of file accesses and the amount of data transferred can be taken to represent the
activity level of a certain user account in the HPSS system. You may wish to charge specifically
for the network and server resources consumed by this activity.
•It may be useful to charge different rates for each Class of Service. For example, a Class of
Service that keeps two tape copies of each file will use up more tape cartridges than a Class of
Service that keeps only a single copy of each file on tape.
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