Red Hat GLOBAL FILE SYSTEM 4.7, Manual

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Specifies the zero-length file where the flag is set or cleared.
Examples
This example shows setting the
inherit_jdata
flag on a directory. All files created in the
directory or any of its subdirectories will have the
jdata
flag assigned automatically. Any data
written to the files will be journaled.
gfs_tool setflag inherit_jdata /gfs1/data/
This example shows setting the
jdata
flag on a file. The file must be zero size. Any data written
to the file will be journaled.
gfs_tool setflag jdata /gfs1/datafile
9. Configuring
atime
Updates
Each file inode and directory inode has three time stamps associated with it:
•
ctime
— The last time the inode status was changed
•
mtime
— The last time the file (or directory) data was modified
•
atime
— The last time the file (or directory) data was accessed
If
atime
updates are enabled as they are by default on GFS and other Linux file systems then
every time a file is read, its inode needs to be updated.
Because few applications use the information provided by
atime
, those updates can require a
significant amount of unnecessary write traffic and file-locking traffic. That traffic can degrade
performance; therefore, it may be preferable to turn off
atime
updates.
Two methods of reducing the effects of
atime
updating are available:
• Mount with
noatime
• Tune GFS
atime
quantum
9.1. Mount with
noatime
A standard Linux mount option,
noatime
, can be specified when the file system is mounted,
which disables
atime
updates on that file system.
Examples
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