Chapter 1 HPSS Basics28 September 2002 HPSS Installation GuideRelease 4.5, Revision 2parallel I/O to that set of resources, and schedules the mounting and dismounting ofremovable media through the Physical Volume Library (see below).• 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 ValidationService.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 toimplement site policy for monitoring authorized callers, creates, opens, and stages. TheBFS will call the appropriate GK API depending on the requests that the site-implementedpolicy is monitoring.The Account Validation Service performs authorizations of user storage charges. A sitemay perform no authorization, default authorization, or site-customized authorizationdepending on how the Accounting Policy is set up and whether or not a site has writtensite-specific account validation code. Clients call this service when creating files, changingfile ownership, or changing accounting information. If Account Validation is enabled, theAccount Validation Service determines if the user is allowed to use a specific account orgives the user an account to use, if needed. The Name Server and Bitfile Server also call thisservice to perform an authorization check just before account-sensitive operations takeplace.• Location Server (LS). The Location Server acts as an information clearinghouse to its clientsthrough the HPSS Client API to enable them to locate servers and gather information fromboth local and remote HPSS systems. Its primary function is to allow a client to determinea server's location, its CDS pathname, by knowing other information about the server suchas its object UUID, its server type or its subsystem id. This allows a client to contact theappropriate 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 betweenDFS and HPSS servers. It translates calls between DFS and HPSS, migrates data from DFSinto HPSS, and validates data in DFS and HPSS. In addition, it maintains records of all DFSand HPSS filesets and their statistics.• Physical Volume Library (PVL). The PVL manages all HPSS physical volumes. It is incharge of mounting and dismounting sets of physical volumes, allocating drive andcartridge resources to satisfy mount and dismount requests, providing a mapping ofphysical volume to cartridge and of cartridge to Physical Volume Repository (PVR), andissuing commands to PVRs to perform physical mount and dismount actions. Arequirement of the PVL is the support for atomic mounts of sets of cartridges for parallelaccess to data. Atomic mounts are implemented by the PVL, which waits until all necessarycartridge resources for a request are available before issuing mount commands to thePVRs.• 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 thestatus and characteristics of cartridges. Every cartridge in HPSS must be managed by
