1.3.2. Additional Differences Between GFS and GFS2
GFS2 file systems support the use of the
chattr command to set and clear the
j flag on a file or directory. Setting the
+j flag on a file enables data journaling on that file. Setting the
+j flag on a directory means "inherit jdata", which indicates that all files and directories subsequently created in that directory are journaled. Using the
chattr command is the preferred way to enable and disable data journaling on a file.
atime_quantum parameter removed
The GFS2 file system does not support the
atime_quantum tunable parameter, which can be used by the GFS file system to specify how often
atime updates occur. In its place GFS2 supports the
noatime mount options. The
relatime mount option is recommended to achieve similar behavior to setting the
atime_quantum parameter in GFS.
The data= option of the mount command
When mounting GFS2 file systems, you can specify the
data=writeback option of the
data=ordered is set, the user data modified by a transaction is flushed to the disk before the transaction is committed to disk. This should prevent the user from seeing uninitialized blocks in a file after a crash. When
data=writeback is set, the user data is written to the disk at any time after it is dirtied. This does not provide the same consistency guarantee as
ordered mode, but it should be slightly faster for some workloads. The default is
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
gfs_edit man pages.