2.5.3. VFS Tuning Options: Research and Experiment

Like all Linux file systems, GFS2 sits on top of a layer called the virtual file system (VFS). You can tune the VFS layer to improve underlying GFS2 performance by using the sysctl(8) command. For example, the values for dirty_background_ratio and vfs_cache_pressure may be adjusted depending on your situation. To fetch the current values, use the following commands:

sysctl -n vm.dirty_background_ratio
sysctl -n vm.vfs_cache_pressure

sysctl -n vm.dirty_background_ratio
sysctl -n vm.vfs_cache_pressure

The following commands adjust the values:

sysctl -w vm.dirty_background_ratio=20
sysctl -w vm.vfs_cache_pressure=500

sysctl -w vm.dirty_background_ratio=20
sysctl -w vm.vfs_cache_pressure=500

You can permanently change the values of these parameters by editing the /etc/sysctl.conf file.

To find the optimal values for your use cases, research the various VFS options and experiment on a test cluster before deploying into full production.