Hub/Switch Installation Guide

Chapter 1 HPSS Basics
28 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
parallel I/O to that set of resources, and schedules the mounting and dismounting of
removable 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. Itprovidessites withtheabilitytovalidateuseraccounts usingthe AccountValidation
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 theappropriateGK APIdepending onthe requeststhatthesite-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 validationcode.Clients call thisservice when creatingfiles, 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
givestheuseranaccount touse,ifneeded.The NameServerandBitfileServer alsocallthis
service to perform an authorization check just before account-sensitive operations take
place.
• LocationServer(LS).TheLocationServeractsasaninformationclearinghousetoitsclients
throughthe HPSSClient API toenablethemto locateservers andgather information from
both local and remote HPSSsystems. Itsprimary function is to allow a client to determine
aserver's location,itsCDSpathname, byknowingother informationabout theserversuch
as its object UUID, its server type or its subsystem id. This allows a client to contact the
appropriateserver. Usually thisisfor theName Server, theBitfileServer orthe 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
intoHPSS, andvalidates datain DFSand HPSS.In addition,it maintainsrecordsofall DFS
and HPSS filesets and their statistics.
• 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
accesstodata.AtomicmountsareimplementedbythePVL,whichwaitsuntilallnecessary
cartridge resources for a request are available before issuing mount commands to the
PVRs.
• 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