HPSS provides an industry-standard FTP user interface. Because FTP is a serial interface, data sent to a user is received serially. This does not mean that the data within HPSS is not stored and retrieved in parallel. It simply means that the FTP daemon within HPSS must consolidate its internal parallel transfers into a serial data transfer to the user. HPSS FTP performance in many cases will be limited not by the speed of a single storage device, as in most other storage systems, but by the speed of the data path between the HPSS FTP daemon and the user's FTP client.
All FTP commands are supported or properly rejected if the HPSS Parallel FTP Daemon does not implement a specific feature. In addition, the ability to specify Class of Service for is provided via the quote site or site commands. Additional site command options are provided for chgrp, chgid, chmod, chown, chuid. stage, wait, and symlink. The HPSS FTP Daemon supports access from any RFC-0959 conformant FTP Client. In addition, the quote allo64 command is supported.
Passive connections are not supported. Also, to avoid potential difficulties, the user should explicitly change the data transfer type to binary. ASCII transfers are very inefficient.
Refer to the HPSS System Administration Guide for information on configuring PFTP.
The PFTP supports normal FTP plus extensions. It is built to optimize FTP performance for storing and retrieving files from HPSS by allowing the data to be transferred in parallel to the client. The interface provided to the user has syntax similar to FTP but with some extensions to allow the user to transfer data to and from HPSS across parallel communication interfaces. PFTP supports transfers either via TCP/IP. The FTP client communicates directly with HPSS Movers to transfer data.
The following constraints are imposed by PFTP.
Passive connections are only supported for parallel push type operations using the PDATA_PUSH protocol.
ASCII transfers are not supported over the parallel interface because ASCII transfers insert characters. This makes it impossible to send the data in parallel. Since extra characters are inserted in the stream, there is no way to resolve data placement. Note that some FTP implementations default to ascii. If this is the case, it will be necessary to specify binary by entering the bin command.
PFTP client access is supported only from nodes which support the HPSS PFTP client software.
HTAR is a non-DCE client utility which manipulates HPSS-resident archives by writing files to, or retrieving files from HPSS. Files written to HPSS are in the POSIX 1003.1 "tar" format and may be retrieved from HPSS or read by native tar programs.
The following constraints are imposed by HTAR:
Reading from or writing to pipes is not supported.
Appending entries to existing archives in not supported.
Updating entries in existing archives is not supported.
Removing entries from existing archives is not supported.
The archival/extraction of symbolic links is not supported.
There is no way to specify relative Index file pathnames that are not rooted in the Archive file directory without specifying an absolute path.
The maximum size of an member in an HTAR archive is 8 GB (2^33 bytes).
The purpose of the NFS V3 server interface is to provide transparent access to HPSS name space object and bitfile data for client systems. Following a mount on the HPSS file system name, the user may access HPSS files using standard function calls and command interfaces.
The code written to implement the NFS V3 Server interface is written to the Network File System Specification, RFC-1813, DDN Network Information Center, SRI International, Menlo Park, Ca.
The NFS V3 Server interface and data structures are defined by RFC-1813.
Since there are no extensions or modifications to the NFS user interface, no additional interface information is provided in the remainder of this document.
The following constraints are imposed by the HPSS NFS V3 server:
All files created using NFS are stored in a single Class of Service. The Class of Service used by NFS is defined by the HPSS administrator.
NFS transfers are slower than the other HPSS interfaces, and are therefore not recommended for large file accesses.
The purpose of the HPSS user utilities is to provide the end user with information such as Access Control List (ACL) definitions and Class of Service definitions. In addition, the ability for a user to change his ACL definitions is provided.
The user utilities consist of these commands:
hacl - edit HPSS Access Control Lists
lshpss - list information for HPSS (Class of Service list, hierarchy list, storage class list, physical volumes, devices and drives, servers, Movers, and other metadata)