Managing the memfs filesystem

Managing the memfs filesystem

The memfs filesystem type is a high-performance, volatile memory filesystem type. The nature of this filesystem type is such that users are able to create directories and files, but, because the filesystem is only in memory, when it is unmounted, the directories and files go away.

When mounting memfs, you can use the -o option to specify file-system-specific options. These file-system-specific options are:

swapmax: swapmax sets the maximum amount of dedicated memory for the file system, in bytes.
global_swapmax: global_swapmax sets the maximum amount of shared memory for all memfs filesystems, in bytes.
rootmode: rootmode specifies the mode of the root directory of mounted memfs. rootmode allows system administrators to set a sticky bit for /tmp and /var/tmp.

The swapmax and global_swapmax options cannot be used together on the same command line. Refer to mount_memfs(ADM) for complete information.

NOTE: Mounting an memfs filesystem creates an instantiation of the filesystem. Therefore, there is no corresponding mkfs command required for the memfs filesystem type.

By default, a emfs filesystem is provided for each of /tmp and /var/tmp on initial system installation, and they share the global_swapmax memory pool. The default value of global_swapmax at system installation is set to the maximum integer value supported by the system.