Data Journaling - Red Hat GLOBAL FILE SYSTEM 5.2 Manual

Chapter 3. Managing GFS
Directory
Specifies the directory where the
Example
In this example, the command sets the
.
/mnt/gfs/data
gfs_tool setflag inherit_directio /mnt/gfs/data
This command displays the flags that have been set for the
output has been truncated.
[root@tng3-1 gfs]# gfs_tool stat /mnt/gfs/data
...
Flags:
inherit_directio

9. Data Journaling

Ordinarily, GFS writes only metadata to its journal. File contents are subsequently written to disk
by the kernel's periodic sync that flushes file system buffers. An
the file's data to be written to disk immediately. The call returns when the disk reports that all
data is safely written.
Data journaling can result in a reduced
data is written to the journal in addition to the metadata. An
data is written to the journal, which can be substantially faster than the time it takes to write the
file data to the main file system.
Applications that rely on
journaling. Data journaling can be enabled automatically for any GFS files created in a flagged
directory (and all its subdirectories). Existing files with zero length can also have data journaling
turned on or off.
Using the command, data journaling is enabled on a directory (and all its
gfs_tool
subdirectories) or on a zero-length file by setting the
the directory or file, respectively. The directory and file attribute flags can also be cleared.
Usage
Setting and Clearing the
32
inherit_directio
inherit_directio
fsync()
to sync file data may see improved performance by using data
fsync()
Flag
inherit_jdata
flag is set.
flag on the directory named
/mnt/gfs/data
fsync()
time, especially for small files, because the file
returns as soon as the
fsync()
or
inherit_jdata
directory. The full
call on a file causes
attribute flags to
jdata