All write activity to a file system can be suspended for a time by using the gfs_tool command's freeze action. The unfreeze action returns the file system to its ordinary state. That feature allows hardware-based device snapshots to be used to capture the file system in a consistent state.
gfs_tool freeze MountPoint
gfs_tool unfreeze MountPoint
Specifies the file system to freeze or unfreeze.
This example freezes file system /gfs.
gfs_tool freeze /gfs
This example unfreezes file system /gfs.
gfs_tool unfreeze /gfs