HP XC System 2.x Software - Manual (Page 21)

choose to use either the HP XC Administrative Network, or the XC system Interconnect, for
NFS operations. The HP XC system interconnect can potentially offer higher performance, but
only at the potential expense of the performance of application communications.
For high-performance or high-availability file I/O, the Lustre file system is available on HP
XC. The Lustre file system uses POSIX-compliant syntax and semantics. The HP XC System
Software includes kernel modifications required for Lustre client services which enables the
operation of the separately installable Lustre client software. The Lustre file server product used
on HP XC is the HP Storage Works Scalable File Share (SFS), which fully supports the HP XC.
The SFS includes HP XC Lustre client software. The SFS can be integrated with the HP XC so
that Lustre I/O is performed over the same high-speed system interconnect fabric used by the
HP XC. So, for example, if the HP XC system interconnect is based on a Quadrics QsNet II
switch, then the SFS will serve files over ports on that switch. The file operations are able to
proceed at the full bandwidth of the HP XC system interconnect because these operations are
implemented directly over the low-level communications libraries. Further optimizations of file
I/O can be achieved at the application level using special file system commands – implemented
as
ioctls – which allow a program to interrogate the attributes of the file system, modify the
stripe size and other attributes of new (zero-length) files, and so on. Some of these optimizations
are implicit in the HP-MPI I/O library, which implements the MPI-2 file I/O standard.
File System Layout
In an HP XC system, the basic file system layout is the same as that of the Red Hat Advanced
Server 3.0 Linux file system.
The HP XC file system is structured to separate cluster-specific files, base operating system
files, and user-installed software files. This allows for flexibility and ease of potential upgrades
of the system software as well as keeping software from conflicting with user installed software.
Files are segregated into the following types and locations:
• HP XC-specific software is located in /opt/hptc
• HP XC configuration data is located in /opt/hptc/etc
• Clusterwide directory structure (file system) is located in /hptc_cluster
You should be aware of the following information about the HP XC file system layout:
• Open source software that by default would be installed under the /usr/local directory
is instead installed in the /opt/hptc directory.
• Software installed in the /opt/hptc directory is not intended to be updated by users.
• Software packages are installed in directories under the /opt/hptc directory under their
own names. The exception to this is 3rd-party software, which usually goes in /opt/r .
• There are four directories under the /opt/hptc directory that contain symbolic links
to files included in the packages:
- /opt/hptc/bin
- /opt/hptc/sbin
- /opt/hptc/lib
- /opt/hptc/man
Each package directory should have a directory corresponding to each of these directories
where every file has a symbolic link created in the
/opt/hptc/ directory.
1.1.5 System Interconnect Network
The HP XC system interconnect provides high-speed connectivity for parallel applications. The
system interconnect network provides a high speed communications path used primarily for
user file service and for communications within user applications that are distributed among
Overview of the User Environment 1-3