IBM General Parallel File System for AIX: Data Management API Guide

Changes for GPFS 1.2

GPFS 1.2 provides several scalability and usability enhancements:

• Migration to a new release of GPFS can be tested on a GPFS configuration. This will ease your migration by allowing you to test the new level of code without inhibiting your production level code. See the IBM General Parallel File System for AIX: Installation and Administration Guide section on GPFS Configurations for Migration.
• An external programming call, which provides the ability to preallocate space for a file, has been added to GPFS. This will allow you to preallocate an amount of space for a file that has already been opened, prior to writing data to the file.
• The number of files possible in a GPFS file system is no longer fixed at file system creation. The number of possible i-nodes (files or directories) may now be increased via the mmchfs command.
• GPFS token management has been moved from the AIX kernel to the GPFS daemon. This provides additional kernel heap storage for system functions and quicker recovery in case of File System Manager failures.
• The file system descriptor limits have been increased. The limit of 512 disk descriptors has been increased to 1024.
• There is increased flexibility in the use of memory. Memory usage for GPFS can be changed by issuing a command without stopping and reinitializing GPFS.
• The maximum file system size supported has been increased. The maximum file system size of 1TB has been increased to 5TB.