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

nfs performance tuning for hp-ux 11.0 and 11i systems page 83

Notes:

Page 83July 22, 2002

cachefs

Application Binary Caching Solutions

(part 1)

• cat(1) Solution

Ø cat(1) the application binary across the CacheFS filesystem and

write it to /dev/null or /dev/zero

Ø Ex: cat /opt/netscape/netscape > /dev/null

Where “/opt/netscape” is the CacheFS-mounted filesystem

Ø Forces CacheFS to read the entire binary file in a single

contiguous chunk

Ø Once the cache is populated, the binary will remain cached

following unmounts and reboots, and all requests for this file will

be satisfied from the cache

Ø Painful to implement on large numbers of clients with many

diverse applications

One way to guarantee that CacheFS stores an application binary, or any other

type of file, in a single contiguous collection of disk space is to read the entire

target file across the CacheFS mount point via the cat(1) command. For example:

cat /cfs_mount/myprog > /dev/null

Using cat in this manner forces CacheFS to read the entire “myprog” file

sequentially, consuming only one slot in the allocation map. Remember, the map

entries consist of a starting offset value and a length field. Therefore, if a 20MB file

is read sequentially across a CacheFS mount, the file can be represented in one

slot (i.e. starting offset = 0, length = 20MB). Once the cat command completes, the

client system has a complete copy of the “myprog” binary in its local filesystem.

This cached binary will survive a CacheFS filesystem unmount or a client reboot.

This is not a very practical solution in most CacheFS environments because there

are typically hundreds, or even thousands, of NFS clients to distribute applications

to, and in many cases the clients will run different sets of applications.