Hub/Switch Installation Guide

Chapter 2 HPSS Planning
58 September 2002 HPSS Installation Guide
Release 4.5, Revision 2
• High Availability HPSS configuration
2.5 HPSS Interface Considerations
This section describes the user interfaces to HPSS and the various considerations that may impact
the use and operation of HPSS.
2.5.1 Client API
The HPSSClient API provides aset of routines thatallow clients to access thefunctions offered by
HPSS. The API consists of a set of calls that are comparable to the file input/output interfaces
definedbythePOSIXstandard(specificallyISO/IEC9945-1:1990or IEEEStandard1003.1-1990),as
well as extensions provided to allow access to the extended capabilities offered by HPSS.
The Client API is built on top of DCE and Encina (which provide threading, transactional RPCs,
and security) and must be run on a platform capable of supporting DCE and Encina client
programs. To access HPSS from client platforms that do not support DCE and Encina clients, the
FTP, Parallel FTP, NFS, Non-DCE Client API, and MPI-IO interfaces can be used.
TheClientAPI allowsclients to specifytheamount ofdata tobetransferredwitheachrequest.The
amount requested can have a considerable impact on system performance and the amount of
metadata generated when writing directly to a tape storage class. See Sections 2.8.6 and 2.11 for
further information.
The details of the Application Programming Interface are described in the HPSS Programmer’s
Reference Guide, Volume 1.
2.5.2 Non-DCE Client API
The Non-DCE Client API provides the same user function calls as the Client API for client
applications who are running on platforms without DCE or Encina with the following exceptions:
• ACL calls are not supported.
• Calls are not transactional.
• It implements its own security interface.
Clientauthenticationisperformedinoneofthreeways:remoteDCElogin,Kerberosauthentication
or no authentication (in case of trusted clients). In order to use the NDAPI, the client application
must link the Non-DCE Client API library, and the target HPSS system must have a Non-DCE
Client Gateway server configured and running. The application calls to the library are then sent
overthenetworkto theNDCG who executestheappropriate ClientAPIcalls, returningtheresults
to the client application. Kerberos must be installed on the client and the gateway in order to use
the Kerberos security feature.