NFS Services Administrator's Guide

Configuring the Cache File System (CacheFS)
The Cache File System
Chapter 3138
The Cache File System
IMPORTANT CacheFS is not available on HP-UX 11.0.
The Cache File System (CacheFS) is a general purpose file system
caching mechanism that improves NFS server performance and
scalability by reducing server and network load. CacheFS provides the
ability to cache one file system on another.
In an NFS environment, CacheFS increases the client per server ratio,
reduces server and network loads, and improves performance for clients
on slow links (for example, PPP).
CacheFS performs local disk caching of file systems, which reduces the
network traffic. Individual client machines become less reliant on the
server, thereby decreasing overall server load, which leads to an increase
in server performance.
CacheFS improves read performance for data that will be read more
than once. It does not improve write performance at all.
Good choices for cached file systems include man pages and executable
programs, which are read multiple times and rarely modified. Using
CacheFS for /var/mail is not a good use of resources. The /var/mail
file is modified frequently and is typically read only once and then
thrown away.
By default, CacheFS maintains consistency with the back file system
using a consistency checking model like that of NFS (polling for changes
in file attributes).
The first time data is read from an NFS-mounted file system, there is
actually some overhead while CacheFS writes the data to its local cache.
After the data is written to the cache, read performance for the file
system is significantly improved.