Hub/Switch Installation Guide
Chapter 2 HPSS Planning
HPSS Installation Guide September 2002 81
Release 4.5, Revision 2
must be in use before purging begins, and a lower bound specifying the target percentage of free
space to reach before purging is stopped.
2.6.17 Non-DCE Client Gateway
TheNon-DCEClient GatewayprovidesHPSSaccess toapplications runningwithoutDCE and/or
Encina which make calls to the Non-DCE Client API. It does this by calling the appropriate Client
APIsitselfand returningthe resultstotheclient. Anysystemwhich wishestomake use ofthe Non-
DCE Client APIs must have a properly configured and running NDCG.
An HPSS installation can have multiple NDCG servers. A client can utilize a particular NDCG
server by setting its HPSS_NDCG_SERVERS environment variable with the hostname and port
of the target NDCG server.
The NDCG can be configured to support client authentication. A single NDCG can be configured
to support Kerberos and/or DCE authentication. The client requests one of the supported
authentication methods during theinitial connection.Clientauthentication can also be completely
disabled on a NDCG server basis. In this case, the NDCG server believes the identity of the client
sentduringtheinitialconnection.WhenusingDCEauthentication,theDCEidentityandpassword
are passed in an encrypted format from client to server during the initial connection. The NDCG
can be configured to support either DES or simple hashing function for encryption of the DCE
identity and password that is passed to the NDCG.
See Section 2.3.4.2: HPSS Non-DCE Mover/Client Machine on page 51 for more information on
prerequisites for a Non-DCE configuration.
2.7 Storage Subsystem Considerations
Storagesubsystems havebeenintroducedinto HPSSforthe purposeof increasingthescalabilityof
the system - particularly with respect to the name and bitfile servers. In releases prior to 4.2, an
HPSS system could only contain a single name and bitfile server. With the addition of storage
subsystems, anHPSS system must nowcontain one ormore storagesubsystems, and eachstorage
subsystem contains its own name and bitfile servers. If multiple name and bitfile servers are
desired, this is now possible by configuring an HPSS system with multiple storage subsystems.
AbasicHPSS systemcontainsasinglestoragesubsystem. Additionalstoragesubsystems allowthe
use of multiple name and bitfile servers, but also introduce additional complexity in the form of
extra subsystems and servers being defined. Storage subsystems can also be used to increase
scalability with respect to SFS, but the price of this is that each storage subsystem requires its own
copies of several metadata files to support the servers in that subsystem. Finally, storage
subsystemsprovideausefulwaytopartitionanHPSSsystem,thoughtheyalsorequirethatstorage
resources be fragmented in order to support the multiple subsystems.
2.8 Storage Policy Considerations
This section describes the various policies that control the operation of the HPSS system.