Filesets
In most file systems, a file hierarchy is represented as a series of directories that form a tree-like structure. Each directory contains other directories, files, or other file-system objects such as symbolic links and hard links. Every file system object has a name associated with it, and is represented in the namespace as a node of the tree.
- Filesets can be used to define quotas on both data blocks and inodes.
- The owning fileset is an attribute of each file and can be specified in a policy to control initial data placement, migration, and replication of the file's data. See Policies for automating file management.
- Fileset snapshots can be created instead of creating a snapshot of an entire file system.
GPFS supports independent and dependent filesets. An independent fileset is a fileset with its own inode space. An inode space is a collection of inode number ranges reserved for an independent fileset. An inode space enables more efficient per-fileset functions, such as fileset snapshots. A dependent fileset shares the inode space of an existing, independent fileset. Files created in a dependent fileset are assigned inodes in the same collection of inode number ranges that were reserved for the independent fileset from which it was created.
When the file system is created, only one fileset, called the root fileset, exists. The root fileset is an independent fileset that cannot be deleted. It contains the root directory as well as any system files such as quota files. As new files and directories are created, they automatically become part of the parent directory's fileset. The fileset to which a file belongs is largely transparent for ordinary file access, but the containing fileset can be displayed along with the other attributes of each file using the mmlsattr -L command.
The root directory of a GPFS file system is also the root of the root fileset.