Red Hat GFS 6.1 -, Руководство администратора

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50 Chapter 5. Managing GFS
File
Specifies the zero-length file where the flag is set or cleared.
5.8.2. 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
5.9. 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 re-
quire 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
5.9.1. 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.