IBM General Parallel File System for AIX: Administration and Programming Reference

Modifying file system attributes

Use the mmchfs command to modify existing file system attributes:

-A

Automatically mount the file system when the GPFS daemon starts

-C

Nodeset to which the file system belongs (see Moving a file system to a new nodeset)

-F

Maximum number of files that can be created

If your file system has additional disks added or the number of inodes was insufficiently sized at file system creation, you may change the number of inodes and hence the maximum number of files that can be created.

The initial setting of the number of inodes at file system creation will be used as the minimum value. The new value, set by using the mmchfs command, will determine the maximum value. The inode file will expand on demand, from the initial minimum value set up to the new maximum value as needed.

-m

Default metadata replication

If your file system availability requirements change, you may want to begin or cease replicating metadata for new files.

-Q

Quota enforcement

Activate or deactivate quota enforcement when the file system is mounted.

-r

Default data replication

If your file system availability requirements change, you may want to begin or cease replicating data for new files.

-T

The mountpoint of the file system starting at the next mount of the file system

-V

The file system format is changed to the latest format supported by the currently installed level of GPFS. This will cause the file system to become permanently incompatible with prior releases of GPFS.

Note:

Changes to the default data and metadata replication attributes apply only to new files created after the attributes change. If you want to change the replication of existing files, you must use the mmchattr command. See Querying and changing file replication attributes.

For example, to change the default data replication factor to 2 for the file system fs1, enter:

mmchfs fs1 -r 2

To confirm the changes, enter:

mmlsfs fs1 -r

The system displays information similar to:

flag value          description
---- -------------- -------------------------------------------------------
-r   2              Default number of data replicas
 

See the mmchfs Command and the mmlsfs Command for complete usage information. See the IBM General Parallel File System for AIX: Concepts, Planning, and Installation Guide and search on GPFS architecture and file system creation considerations for a detailed discussion of file system attributes.