Red Hat Knowledgebase

A GFS filesystem can be mounted on one machine without the need to start the cluster services. The trick is to use the "lock_nolock" locking protocol.

There are a number of ways to do this:

1. Via gfs_tool
   1. Make sure that the GFS module is loaded:

      modprobe gfs
      

   2. To prepare GFS for the actual mount command, execute:

      gfs_tool margs lockproto=lock_nolock
      

   3. Mount the GFS filesystem, like so:

      mount -t gfs /dev/VolGroup00/LogVol01 /mount/point
      

      The gfs_tool command has to be performed for each GFS filesystem to be mounted. For example:

      gfs_tool margs lockproto=lock_nolock
      mount -t gfs /dev/VolGroup00/LogVol02 /mount/data
      gfs_tool margs lockproto=lock_nolock
      mount -t gfs /dev/VolGroup00/LogVol03 /mount/shared
      

2. Directly mounting

   Another way to achieve the same result is to pass the lockproto option during mounting. The example above can be accomplished with the following commands:

   mount -t gfs /dev/VolGroup00/LogVol02 /mount/data -o lockproto=lock_nolock
   mount -t gfs /dev/VolGroup00/LogVol03 /mount/shared -o lockproto=lock_nolock
   

   Again, make sure that the gfs module is loaded before mounting.

Note: This proves useful for situations where the cluster is down and data needs to be accessed from GFS or for back-up purposes. Another machine with an attached tape device can also mount the gfs and back it up.

Warning: Although the gfs mount will be accessible to other machines, do not mount with the lock_nolock option on multiple machines at the same time or the data will be corrupted.