NFS Performance Tuning for HP-UX 11.0 and 11i Systems

nfs performance tuning for hp-ux 11.0 and 11i systems page 77

Notes:

Page 77July 22, 2002

cachefs

What is CacheFS? (part 1)

• An NFS filesystem caching mechanism

• Stores data retrieved from NFS servers to a local

filesystem on the NFS client

• Intended to eliminate the need for retrieving data across

the network that has already been read, thereby

reducing network overhead and increasing the

client-to-server ratio

Difference between 11.0 and 11i

CacheFS is not available on 11.0 – it is available on 11i

Since NFS is a file access protocol, one of the primary goals of NFS performance

tuning is to reduce the amount of network traffic required to satisfy read requests.

One method of reducing read traffic is to use client-side buffer cache and page

cache to store the most recently accessed data. However, since physical memory

is limited in size, the caching mechanisms often have to flush pages and retrieve

them again from the server. Also, as more NFS clients are added to a given

server, the file access times for each client increases, perpetuating the server

performance load and impacting the overall network performance.

CacheFS (Cache File System) attempts to address these needs by keeping copies of

data read from NFS servers on the client in the hopes of avoiding the need for

future NFS read calls for the same data. CacheFS is a file system caching

mechanism that stores data retrieved from NFS servers to a local filesystem on the

client. NFS read requests for data residing in the cache directory can be retrieved

locally, thereby eliminating the need for a network request and reducing overall

server and network load. CacheFS is intended to increase the client-to-server ratio,

and improve NFS read performance for clients using slow network links.