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3.11.5. Client API
The Client API provides the capability to perform data transfer of any size (the size being parameters
supplied by the client to the read and write interfaces). The size of the data transfers can have a
significant impact on the performance of HPSS. In general, larger transfers will generate less
overhead than a series of smaller transfers for the same total amount of data.
The size of the transfers is extremely important because the clients may write files directly to a tape
Storage Class, as described in Section 3.11.3: Configuration on page 113.
3.11.6. Core Server
Minor performance degradations may be seen when the Core Server is processing path names with a
large number of components, servicing requests for objects which have a large number of Object
ACL entries, and servicing create requests for objects which have Initial Container/Initial Object
ACL entries.
3.11.7. Location Server
The Location Policy defined for a site generally determines how the Location Server will perform
and how it will impact the rest of the HPSS system. View the help for the fields on this screen to
determine if the values need to be changed. The default policy values are adequate for the majority
of sites. Usually, the only time the policy values need to be altered is when there is unusual HPSS
setup.
The Location Server itself will give warning when a problem is occurring by posting alarms to SSM.
Obtain the information for the Location Server alarms listed in the HPSS Error Manual. To get a
better view of an alarm in its context, view the Location Server's statistics screen.
If the Location Server consistently reports a heavy load condition, increase the number of request
threads and recycle the Location Server. Remember to increase the number of threads on the
Location Server's basic server configuration screen as well. If this doesn't help, consider replicating
the Location Server on a different node. Note that a heavy load on the Location Server should be a
very rare event.
3.11.8. Logging
Excessive logging by the HPSS servers can degrade the overall performance of HPSS. If this is the
case, it may be desirable to limit the message types that are being logged by particular servers. The
Logging Policy can be updated to control which message types are logged. A default Log Policy may
be specified to define which messages are logged. Typically, Trace, Security, Accounting, Debug,
and Status messages are not logged. Other message types can also be disabled. Once the Logging
Policy is updated for one or more HPSS servers, the Log Clients associated with those servers must
be reinitialized.
3.11.9. Cross Realm Trust
Cross Realm Trust should be established with the minimal reasonable set of cooperating partners.
Excessive numbers of Cross Realm connections may diminish security and cause performance
problems due to Wide Area Network delays. The communication paths between cooperating realms
should be reliable.
3.11.10. Gatekeeping
Sites may choose to implement site policy in the Gatekeeper for load balancing create, open, and/or
HPSS Installation Guide July 2008
Release 6.2 (Revision 2.0) 115