Chapter 5. GFS2 file system repair

When nodes fail with the file system mounted, file system journaling allows fast recovery. However, if a storage device loses power or is physically disconnected, file system corruption may occur. (Journaling cannot be used to recover from storage subsystem failures.) When that type of corruption occurs, you can recover the GFS2 file system by using the fsck.gfs2 command.

Important

The fsck.gfs2 command must be run only on a file system that is unmounted from all nodes. When the file system is being managed as a Pacemaker cluster resource, you can disable the file system resource, which unmounts the file system. After running the fsck.gfs2 command, you enable the file system resource again. The timeout value specified with the --wait option of the pcs resource disable indicates a value in seconds.

# pcs resource disable --wait=timeoutvalue resource_id
[fsck.gfs2]
# pcs resource enable resource_id

To ensure that fsck.gfs2 command does not run on a GFS2 file system at boot time, you can set the run_fsck parameter of the options argument when creating the GFS2 file system resource in a cluster. Specifying "run_fsck=no" will indicate that you should not run the fsck command.

5.1. Determing required memory for running fsck.gfs2

Running the fsck.gfs2 command may require system memory above and beyond the memory used for the operating system and kernel. Larger file systems in particular may require additional memory to run this command.

The following table shows approximate values of memory that may be required to run fsck.gfs2 file systems on GFS2 file systems that are 1TB, 10TB, and 100TB in size with a block size of 4K.

GFS2 file system sizeApproximate memory required to run fsck.gfs2

1 TB

0.16 GB

10 TB

1.6 GB

100 TB

16 GB

Note that a smaller block size for the file system would require a larger amount of memory. For example, GFS2 file systems with a block size of 1K would require four times the amount of memory indicated in this table.

5.2. Repairing a gfs2 filesystem

The following shows the format of the fsck.gfs2 command to repair a GFS2 filesystem.

fsck.gfs2 -y BlockDevice
-y
The -y flag causes all questions to be answered with yes. With the -y flag specified, the fsck.gfs2 command does not prompt you for an answer before making changes.
BlockDevice
Specifies the block device where the GFS2 file system resides.

In this example, the GFS2 file system residing on block device /dev/testvg/testlv is repaired. All queries to repair are automatically answered with yes.

# fsck.gfs2 -y /dev/testvg/testlv
Initializing fsck
Validating Resource Group index.
Level 1 RG check.
(level 1 passed)
Clearing journals (this may take a while)...
Journals cleared.
Starting pass1
Pass1 complete
Starting pass1b
Pass1b complete
Starting pass1c
Pass1c complete
Starting pass2
Pass2 complete
Starting pass3
Pass3 complete
Starting pass4
Pass4 complete
Starting pass5
Pass5 complete
Writing changes to disk
fsck.gfs2 complete