HP-UX Memory File System (MemFS) 2.0

Installing, Configuring, Tuning, and Removing HP-UX Memory File System
Configuring Memory File System
Chapter 216
Configuring Memory File System
A MemFS instance requires allocation of a memory area to be associated with it, whose size is
equal to the size of the MemFS file system instance. The mount command will fail if it cannot
allocate enough memory. Sufficient disk space must be configured to the system swap device
for mount to succeed. If the MemFS file system size to be created is large (greater than 2 GB),
the tunable maxdsiz_64bit must be tuned appropriately. This memory area is allocated in
the user address space of a process that is forked off the mount command for every mount.
The maximum number of MemFS file system instances supported in HP-UX 11i v2 is 64.
A MemFS instance can be created either through a mount(1) command, or automatically
through an entry in the /etc/fstab file. Creation of a MemFS instance through the
mount(2) system call is not supported.
The syntax for mounting a MemFS instance using the mount(1) command is:
# /usr/sbin/mount -F memfs [-eQV] [-o size=<size>] directory
For example, to create a MemFS instance of size 100MB and mounting it on /memfs:
# /usr/sbin/mount -F memfs -o size=100MB /memfs
The optional size argument can be used to specify the size of a MemFS instance. Append to
size, kb or KB to indicate the value is in kilobytes, mb or MB to indicate megabytes, or gb or
GB to indicate gigabytes. If the size option is not specified, the default size is computed as the
percentage of maximum buffer cache size that can be occupied by MemFS, as specified by the
memfs_bufcache_swappct tunable.
A MemFS instance can be destroyed through a umount(1) command. Only the directory
mount point is required as an argument:
# /usr/sbin/umount /memfs