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Chapter 1
HPSS Basics
parallel I/O to that set of resources, and schedules the mounting and dismounting of
removable media through the Physical Volume Library (see below).
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Gatekeeper Server (GK). The Gatekeeper Server provides two main services:
A. It provides sites with the ability to schedule the use of HPSS resources using the Gate-
keeping Service.
B. It provides sites with the ability to validate user accounts using the Account Validation
Service.
Both of these services allow sites to implement their own policy.
The default Gatekeeping Service policy is to not do any gatekeeping. Sites may choose to
implement site policy for monitoring authorized callers, creates, opens, and stages. The
BFS will call the appropriate GK API depending on the requests that the site-implemented
policy is monitoring.
The Account Validation Service performs authorizations of user storage charges. A site
may perform no authorization, default authorization, or site-customized authorization
depending on how the Accounting Policy is set up and whether or not a site has written
site-specific account validation code. Clients call this service when creating files, changing
file ownership, or changing accounting information. If Account Validation is enabled, the
Account Validation Service determines if the user is allowed to use a specific account or
gives the user an account to use, if needed. The Name Server and Bitfile Server also call this
service to perform an authorization check just before account-sensitive operations take
place.
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Location Server (LS). The Location Server acts as an information clearinghouse to its clients
through the HPSS Client API to enable them to locate servers and gather information from
both local and remote HPSS systems. Its primary function is to allow a client to determine
a server's location, its CDS pathname, by knowing other information about the server such
as its object UUID, its server type or its subsystem id. This allows a client to contact the
appropriate server. Usually this is for the Name Server, the Bitfile Server or the Gatekeeper.
•
DMAP Gateway (DMG). The DMAP Gateway acts as a conduit and translator between
DFS and HPSS servers. It translates calls between DFS and HPSS, migrates data from DFS
into HPSS, and validates data in DFS and HPSS. In addition, it maintains records of all DFS
and HPSS filesets and their statistics.
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Physical Volume Library (PVL). The PVL manages all HPSS physical volumes. It is in
charge of mounting and dismounting sets of physical volumes, allocating drive and
cartridge resources to satisfy mount and dismount requests, providing a mapping of
physical volume to cartridge and of cartridge to Physical Volume Repository (PVR), and
issuing commands to PVRs to perform physical mount and dismount actions. A
requirement of the PVL is the support for atomic mounts of sets of cartridges for parallel
access to data. Atomic mounts are implemented by the PVL, which waits until all necessary
cartridge resources for a request are available before issuing mount commands to the
PVRs.
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Physical Volume Repository (PVR). The PVR manages all HPSS cartridges. Clients (e.g.,
the PVL) can ask the PVR to mount and dismount cartridges. Clients can also query the
status and characteristics of cartridges. Every cartridge in HPSS must be managed by
28
September 2002
HPSS Installation Guide
Release 4.5, Revision 2
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