PIOUS for PVM
		    (Parallel I/O System for PVM)

			    Version 1.2.2


Description
-----------

PIOUS is a complete Parallel I/O System for the PVM distributed computing
environment.  Just as PVM implements a virtual multicomputer on top
of a heterogeneous network of computing resources, PIOUS implements a fully
functional parallel file system on top of PVM.  PVM applications obtain
transparent access to shared permanent storage via PIOUS library functions.

PIOUS is intended to serve both as a platform for supporting high-performance
parallel applications, and as a vehicle for parallel file system research.
PIOUS implements the traditional functionality found in most parallel
computer file systems, as well as a number of unique features, including:

    * Two-dimensional file objects and logical file views

    * Coordinated file access with guaranteed consistency semantics

    * Data declustering for scalable performance

    * Transaction support and user-selectable fault tolerance modes

    * Extended file maintenance primitives for managing declustered files

    * C and Fortran language bindings


PIOUS should work on most systems that support PVM 3.  To date, PIOUS has been
tested on the following:  Sun4/SunOS 4.1.3/5.3-4, SGI/IRIX 4.0.5/5.3,
Dec Alpha/OSF1 2.1, HP 9000/HP-UX, and IBM RS6000/AIX.
Versions of PIOUS are installed at hundreds of sites, and the software
appears to be stable.

The PIOUS distribution comes complete with a user's guide and reference
manual as well as on-line man pages.  Automatic build scripts similar
to those supplied with PVM are provided as well.

PIOUS can be obtained by pointing your favorite WWW browser at the home page
located at http://www.mathcs.emory.edu/pious.html.  Alternatively, PIOUS
can be obtained via anonymous ftp from ftp.mathcs.emory.edu in the
directory pub/pious1; the README file located there provides complete
information on getting and installing the software.


New features
------------

PIOUS 1.2.2 implements the following improvements over the previous version:

 *  Data server scheduling algorithms have been updated to improve performance
    for heavily conflicting accesses; in addition, a previous scheduler bug
    has been corrected.

 *  Data server caching has been changed to implement a Segmented LRU
    algorithm so as to limit the cache flooding caused by extended sequential
    access patterns.

The PIOUS user interface remains unchanged from version 1.2.1.

Regards,

Steven Moyer
Vaidy Sunderam