General Parallel File System
Presentation by:
Lokesh Pradhan
Introduction
 File System
 Way to organize data which is expected to be retained after the
program terminates by providing procedures to store, retrieve
and update data as well as manage the available space on the
device which contains it.
Types of File System
Types
Examples
Disk file system
FAT, exFAT, NTFS…
Optical discs
CD, DVD, Blu-ray
Tape file system
IBM’s Linear tape
Database file system
DB2
Transactional file system
TxF, Valor, Amino,TFFS
Flat file system
Amazon’s S3
Cluster file system
• Distributed file system
• Shared file system
• San file system
• Parallel file system
NFS, CIFS, AFS, SMB, GFS, GPFS,
LUSTRE, PAS
In HPC world
 Equally large applications
 Large input data set (e.g. astronomy data)
 Parallel execution on large clusters
 Use parallel file systems for scalable I/O
 e.g. IBM’s GPFS, Sun’s Lustre FS, PanFS, and
Parallel Virtual File System (PVFS)
General Parallel File System
 Cluster: 512 nodes today, fast
reliable communication
 Shared disk: all data and metadata
on disk accessible from any node
through disk I/O interface (i.e.,
"any to any" connectivity)
 Parallel: data and metadata flows
from all of the nodes to all of the
disks in parallel
 RAS: reliability, accessibility,
serviceability
History of GPFS
 Shark video server
 Video streaming from single RS/6000
 Complete system, included file system, network driver, control server
 Large data blocks, admission control, deadline scheduling
 Bell Atlantic video-on-demand trial (1993-94)
 Tiger Shark multimedia file system
 Multimedia file system for RS/6000 SP
 Data striped across multiple disks, accessible from all nodes
 Hong Kong and Tokyo video trials, Austin video server products
 GPFS parallel file system
 General purpose file system for commercial and technical computing
on RS/6000 SP, AIX and Linux clusters.
 Recovery, online system management, byte-range locking, fast prefetch, parallel allocation, scalable directory, small-block random
access.
 Released as a product 1.1 - 05/98.
What is Parallel I/O?
 Multiple processes
(possibly on multiple
nodes) participate in the
I/O
 Application level
parallelism
 “File” is stored on
multiple disks on a
parallel file system
Compute Nodes
Interconnect
I/O Server Nodes
Disk
What does Parallel System support?
 A parallel file system must support
 Parallel I/O
 Consistent global name space across all nodes of the cluster
 Including maintaining a consistent view across all nodes
for the same file
 Programming model allowing programs to access file data
 Distributed over multiple nodes
 From multiple tasks running on multiple nodes
 Physical distribution of data across disks and network
entities eliminates bottlenecks both at the disk interface and
the network, providing more effective bandwidth to the I/O
resources
Why use general parallel file systems?
 Native AIX File System
• No file sharing - application can only access files on its own node
• Applications must do their own data partitioning
• Distributed File System
•Application nodes (DCE clients) share files on server node
•Switch is used as a fast LAN
•Coarse-grained (file or segment level) parallelism
•Server node : performance and capacity bottleneck
• GPFS Parallel File System
• GPFS file systems are striped across multiple disks on multiple
storage nodes
• Independent GPFS instances run on each application node
• GPFS instances use storage nodes as "block servers" - all instances
can access all disks
Performance advantages with GPFS
file system
 Allowing multiple processes or applications on all
nodes in the cluster simultaneously
 Access to the same file using standard file system calls.
 Increasing aggregate bandwidth of your file system by
spreading reads and writes across multiple disks.
 Balancing the load evenly across all disks to maximize
their combined throughput. One disk is no more active
than another.
Performance advantages with GPFS
file system (cont.)
 Supporting very large file and file system sizes.
 Allowing concurrent reads and writes from multiple
nodes.
 Allowing for distributed token (lock) management.
Distributing token management reduces system
delays associated with a lockable object waiting to
obtaining a token.
 Allowing for the specification of other networks for
GPFS daemon communication and for GPFS
administration command usage within your cluster.
GPFS Architecture Overview
 Implications of Shared Disk Model
 All data and metadata on globally accessible disks
(VSD)
 All access to permanent data through disk I/O
interface
 Distributed protocols, e.g., distributed locking,
coordinate disk access from multiple nodes
 Fine-grained locking allows parallel access by
multiple clients
 Logging and Shadowing restore consistency after
node failures
GPFS Architecture Overview (cont.)
 Implications of Large Scale
 Support up to 4096 disks of up to 1 TB each (4
Petabytes)
 The largest system in production is 75 TB
 Failure detection and recovery protocols to
handle node failures
 Replication and/or RAID protect against disk /
storage node failure
 On-line dynamic reconfiguration (add, delete,
replace disks and nodes; rebalance file system)
GPFS Architecture - Special Node Roles
 Three types of nodes:
File system nodes
Manager nodes
Storage nodes
Disk Data Structures:
 Large block size allows efficient use of disk bandwidth
 Fragments reduce space overhead for small files
 No designated "mirror", no fixed placement function:
Flexible replication (e.g., replicate only metadata, or only important
files)
Dynamic reconfiguration: data can migrate block-by-block
Multi level indirect blocks
• Each disk address:
•List of pointers to replicas
• Each pointer:
•Disk id + sector no.
Availability and Reliability
 Eliminate single point of failures
 Designed to transparently fail over token (lock) operations.
 Supports data replications to increase availability in the vent
of a storage media failure.
 Offers time-tested reliability and has been installed on
thousands of nodes across industries
 Basis of many cloud storage offerings
GPFS’s Achievement
 Used on six of the ten most powerful supercomputers in
the world, including the largest (ASCI white)
 Installed at several hundred customer sites, on clusters
ranging from a few nodes with less than a TB of disk, up
to 512 nodes with 140 TB of disk in 2 file systems
 20 filed patents
 ASC Purple Supercomputer which is composed of more
than 12,000 processors and has 2 PB of total disk storage
spanning more than 11,000 disks.
Conclusion
 Efficient for managing data volumes
 Provides world-class performance, scalability and
availability for your file data
 Designed to optimize the use of storage
 Provide highly available platform for data-intensive
applications
 Delivering real business needs by streamline data
workflows, improvised services reducing cost and
managing the risks.
References

"File System." Wikipedia, the Free Encyclopedia. Web. 20 Jan. 2012.
<http://en.wikipedia.org/wiki/File_system>.

"IBM General Parallel File System for AIX: Administration and Programming Reference Contents." IBM General Parallel File System for AIX. IBM. Web. 20 Jan. 2012.
<https://support.iap.ac.cn/hpc/ibm/ibm/gpfs/am3admst02.html>.

"IBM General Parallel File System." Wikipedia, the Free Encyclopedia. Web. 20 Jan. 2012.
<http://en.wikipedia.org/wiki/IBM_General_Parallel_File_System>.

Intelligent Storage Management with IBM General Parallel File System. Issue brief. IBM, July
2010. Web. 21 Jan. 2012. <http://www-03.ibm.com/systems/software/gpfs/>.

Mandler, Benny. Architectural and Design Issues in the General Parallel File System. IBM
Haita Research Lab, May 2005. Web. 21 Jan. 2012. <Architectural and Design Issues in the
General Parallel File System>.

"NCSA Parallel File Systems." National Center for Supercomputing Applications at the
University of Illinois. University of Illinois, 20 Mar. 2008. Web. 21 Jan. 2012.
<http://www.ncsa.illinois.edu/UserInfo/Data/filesystems/>.

Parallel File System. Rep. Dell Inc., May 2005. Web. 21 Jan. 2012.
<www.dell.com/powersolutions>.

Welch, Brent. "What Is a Cluster Filesystem?" Brent B Welch. Web. 21 Jan. 2012.
<http://www.beedub.com/clusterfs.html>.
Questions?