HP-UX Memory File System

Memory Filesystem provides users with a filesystem that is memory-based. The filesystem offers great performance boost as the disk updations of data and metadata are avoided (unless there is high memory pressure). In the case of heavy memory pressure, data is paged to the system swap device.




	NOTE: MemFS is a Software Pack (SPK) product available on the web. It is not available on the HP-UX 11i v2 Operating Environments (OEs) media. For more information, see “Software Pack (Optional HP-UX 11i v2 Core Enhancements)”.

Summary of Change

MemFS v2 on HP-UX 11iv2 differs from MemFS v1 on HP-UX 11iv2 in the following ways:

It does not require a separate swap device. It will implicitly use the system swap device for swapping.
It uses user process anonymous memory and buffer cache to store MemFS pages.
Ignite-UX supports MemFS.
MemFS filesystems can be recreated through /etc/fstab entries without preserving content.
Provides information of resource usage through sar and GlancePlus.
Contains bug fixes.

Impact

MemFS v2 will allow the customer to mount a MemFS instance without the need of a separate swap device (unlike MemFS v1).

Compatibility

MemFS v1 needs to be uninstalled before MemFS v2 is installed.

Performance

MemFS v2 performance is similar to MemFS v1 performance in non-swapping conditions.

Documentation

For further information, see the following:

White paper: “MemFS v2 – A Memory-based File System on HP-UX 11i v2,” available at
http://docs.hp.com/en/11885/MemFSv2forHP-UX11iv2.pdf
Administrator's Guide: HP-UX Memory File System (MemFS) 2.0 Administrator’s Guide Second Edition, available at
http://www.docs.hp.com/en/5992-2360/5992-2360.pdf

Obsolescence

Not applicable.