Gatekeeper - IBM Hub/Switch Installation Manual

Chapter 2 HPSS Planning
MPS provides the capability of generating migration/purge report files that document the
activities of the server. The specification of the UNIX report file name prefix in the MPS server
specific configuration enables the server to create these report files. It is suggested that a complete
path be provided as part of this file name prefix. Once reporting is enabled, a new report file is
started every 24 hours. The names of the report files are made up of the UNIX file name prefix from
the server specific configuration, plus a year-month-day suffix. With reporting enabled, MPS will
generate file-level migration and purge report entries in real time. These report files can be
interpreted and viewed using the mps_reporter utility. Since the number and size of the report files
grow rapidly, each site should develop a cron job that will periodically remove the reports that are
no longer needed.
MPS uses threads to perform the migration and purge operations and to gather the storage class
statistics from the Storage Servers. In particular, MPS spawns one thread for each disk or tape
storage class on which migration is enabled and one thread for each disk storage class on which
purge is enabled. These threads are created at startup time and exist for the life of the MPS. During
disk migration runs, MPS spawns an additional number of temporary threads equal to the product
of the number of copies being made (determined by the storage hierarchy configuration) and the
number of concurrent threads requested for migration (configured in the Request Count field in the
migration policy). During tape migration runs, MPS spawns one temporary thread for each Tape
Storage Server within its configured subsystem. These threads exist only for the duration of a disk
or tape migration run. Purge does not use any temporary threads. MPS uses a single thread to
monitor the usage statistics of all of the storage classes. This thread also exists for the life of the MPS.
MPS provides the information displayed in the HPSS Active Storage Classes window in SSM.
Each MPS contributes storage class usage information for the resources within its storage
subsystem. MPS accomplishes this by polling the Storage Servers within its subsystem at the
interval specified in the MPS server specific configuration. The resulting output is one line for each
storage class for each storage subsystem in which that class is enabled. The MPS for a subsystem
does not report on classes which are not enabled within that subsystem. MPS also activates and
deactivates the warning and critical storage class thresholds.
Because the MPS uses the BFS and any Storage Servers within its assigned storage subsystem to
perform data movement between hierarchy levels, the BFS and the Storage Servers must be
running in order for the MPS to perform its functions. In addition, the MPS requires that the Storage
Servers within its subsystem be running in order to report storage class usage statistics.
2.6.6

Gatekeeper

Each Gatekeeper may provide two main services:
1. Providing sites with the ability to schedule the use of HPSS resources using Gatekeeping
Services.
2. Providing sites with the ability to validate user accounts using the Account Validation
Service.
If the site doesn't want either service, then it is not necessary to configure a Gatekeeper into the
HPSS system.
Sites can choose to configure zero (0) or more Gatekeepers per HPSS system. Gatekeepers are
associated with storage subsystems. Each storage subsystem can have zero or one Gatekeeper
associated with it and each Gatekeeper can support one or more storage subsystems. Gatekeepers
68 September 2002 HPSS Installation Guide
Release 4.5, Revision 2