IBM General Parallel File System for AIX: Data Management API Guide
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GPFS 1.3 provides several performance, scalability and usability
enhancements. For technical information on these enhancements see the
GPFS for AIX: Installation and Tuning Guide, the GPFS
for AIX: Guide and Reference, and the IBM General Parallel
File System for AIX: Data Management API Guide.
- The term Stripe Group Manager has been replaced by the term
File System Manager.
- The term GPFS configuration has been replaced by the term
GPFS nodeset.
- The term stripe group panic has been replaced by the term
file system forced unmount.
- Possible maximum values for file size and file system size have been
relaxed. The introduction of multiple levels of indirection allows file
sizes up to the largest supported GPFS file system size. The supported
value for maximum file system size has increased to 9TB.
With the use of multiple levels of indirection, GPFS now internally
controls the values for indirect block size and i-node size. System
control of these values allows for more effective caching of i-nodes and may
improve the performance of some applications. The -I
IndirectSize and -i InodeSize options have been
removed from the mmcrfs command.
- GPFS exploits the Low-Level Application Programming Interface (LAPI)
function of the Parallel System Support Program (PSSP). Using LAPI
instead of Transmission Control Protocol/Internet Protocol (TCP/IP) should
improve the performance of communication between the GPFS daemons.
However, it is important you understand what is required when choosing LAPI
as the communications protocol. A switch adapter window must be
reserved on each node in the GPFS nodeset. To successfully reserve an
adapter window for use by GPFS, all LoadLeveler jobs must be
stopped prior to issuing either the mmconfig command or the
mmchconfig command. If LoadLeveler is not stopped, it will
reserve all adapter windows for its use. If an adapter window cannot be
reserved on each node for use by GPFS, the GPFS commands will fail.
- GPFS exploits the SP Security Services Library routines.
- The GPFS File System Manager may be migrated to a specific node.
- GPFS file systems may now be exported via the Distributed File Service
(DFS) protocol.
- A series of interfaces which will allow the Message Passing Interface
(MPI) layer of an application to specify characteristics of its data access
and allow GPFS to optimize its access to the data.
- GPFS file systems can now be managed and monitored by using the Data
Management Application Programming Interface (DMAPI) for GPFS. The
interface is compliant with The Open Group's XDSM standard (System
Management: Data Storage Management (XDSM) API).
- The mmcrvsd command is now available to create virtual shared
disks for use by GPFS. It is suggested that this command be used to
create virtual shared disks for the mmcrfs, mmadddisk,
mmchdisk, and the mmrpldisk commands.
- The mmdefragfs command is now available to reduce disk
fragmentation thereby potentially increasing the number of full free blocks
available to the file system.
- The mmshutdown command is now available to cleanly
unmount all file system and shutdown GPFS either on a single node or
across a set of nodes.
- The mmchdisk command has been enhanced to allow all disks
belonging to a file system to be resumed or started at the same time.
- The mmadddisk, mmchdisk, mmdeldisk,
mmrpldisk, mmrestripefs commands have been enhanced to allow
the user to specify which nodes of a GPFS nodeset will participate in the
restripe of a file system.
- Additional block sizes of 512KB and 1024KB are supported. These
larger block size values may allow you to improve performance by matching RAID
block sizes.
- GPFS programming interfaces now support both 32-bit and 64-bit
applications.
- An external programming call, which provides exact status for a file, has
been added to GPFS. Exact status for a file using the file descriptor
(gpfs_fstat( )) or the file system name (gpfs_stat( ) ), can
now be obtained.
- The mmaddnode, mmchconfig, mmconfig,
mmcrfs, mmdelnode, and mmlsnode commands are now
executable from any node running GPFS or the control workstation. Each
of these GPFS command now has a -C nodeset_Id option which
allows you to designate which GPFS nodeset the command is to act upon.
If this option is not specified when issued from a node, the
command will act upon the nodeset to which the issuing node belongs.
This option must be specified when the command is issued from the
control workstation, or it will fail.
- Because file system names must be unique across nodesets. the
mmadddisk, mmchdisk, mmchfs, mmchmgr,
mmdefragfs, mmdeldisk, mmdelfs, mmdf,
mmfsck, mmlsdisk, mmlsfs, mmlsmgr,
mmrestripefs, and mmrpldisk commands are executable from any
node running GPFS or the control workstation (CWS).
- The mmcheckquota command has been expanded to allow replacement
of the user and group quota files for a file system.
- Support for the following memory mapped file capabilities as described in
the X/OPEN 4.2 standard:
- mmap
- munmap
- msync
- Support for the shmat memory mapped file capability as described in AIX
.
- Support for the fsize user process resource limit, as defined by
ulimit.
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