Gfs2 Performance Improvements - Red Hat ENTERPRISE LINUX 5 - GLOBAL FILE SYSTEM 2 Manual

The gfs2_tool command
The gfs2_tool command supports a different set of options for GFS2 than the gfs_tool command
supports for GFS:
• The gfs2_tool command supports a journals parameter that prints out information about the
currently configured journals, including how many journals the file system contains.
• The gfs2_tool command does not support the counters flag, which the gfs_tool command
uses to display GFS statistics.
• The gfs2_tool command does not support the inherit_jdata flag. To flag a directory as
"inherit jdata", you can set the jdata flag on the directory or you can use the chattr command
to set the +j flag on the directory. Using the chattr command is the preferred way to enable and
disable data journaling on a file.
The gfs2_edit command
The gfs2_edit command supports a different set of options for GFS2 than the gfs_edit command
supports for GFS. For information on the specific options each version of the command supports, see
the gfs2_edit and gfs_edit man pages.

1.2.3. GFS2 Performance Improvements

There are many features of GFS2 filesystems that do not result in a difference in the user interface
from GFS file systems but which improve file system performance.
A GFS2 filesystem provides improved file system performance in the following ways:
• Better performance for heavy usage in a single directory.
• Faster synchronous I/O operations
• Faster cached reads (no locking overhead)
• Faster direct I/O with preallocated files (provided I/O size is reasonably large, such as 4M blocks)
• Faster I/O operations in general
• Execution of the df command is much faster, because of faster statfs calls.
• The atime mode has been improved to reduce the number of write I/O operations generated by
atime when compared with GFS.
GFS2 file systems provide broader and more mainstream support in the following ways.
• GFS2 is part of the upstream kernel (integrated into 2.6.19).
• GFS2 supports the following features:
• SELinux extended attributes.
• the lsattr() and chattr() attribute settings via standard ioctl() calls.
• nanosecond timestamps
A GFS2 file system provides the following improvements to the internal efficiency of the file system.
GFS2 Performance Improvements
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