Managing NFS and KRPC Kernel Configurations in HP-UX 11i v3 (762807-001, March 2014)

Restrictions on Changing
2.1.3 nfs_enable_write_behind
Description
The nfs_enable_write_behind tunable controls the write behind feature when writing to files over NFS.
When the write behind feature is enabled, over-the-wire NFS writes are scheduled by the
writer/application thread. While this can result in NFS write data being sent to the server more
frequently, the server is not affected by the frequent arrival of writes.
Tested Values
Default: 0 (NFS write-behind is disabled)
Min: 0
Max: 1 (NFS write-behind is enabled)
Restrictions on Changing
The nfs_enable_write_behind tunable is dynamic. System reboot is not required to activate a change
made to this tunable.
Modifying the Value
Enable this tunable to enable write behind behavior where over-the-wire NFS writes are scheduled by
the writer/application thread. With some NFS servers, enabling the write behind feature results in
improved write performance. However, the performance of many NFS server implementations
depends heavily on data packets arriving in order. Thus write performance could potentially suffer
when the write behind feature is enabled.
HP recommends changing this tunable only if you can verify your NFS server is not affected by the
frequent arrival of writes. Some NFS servers will benefit from using write behind, but write behind
could degrade the performance of other servers.
2.1.4 nfs_nacache
Description
The nfs_nacache tunable controls the size of the hash structures that manage the file access cache on
the NFS client. The tunable controls the size of the hash structures for NFS filesystems. The file access
cache stores file access rights for users. By default, the algorithm assumes a single access cache entry
per active file.
Tested Values
Default: 0
Min: 0
Max: 40000
Note: If the value of nfs_nacache is set to default, the value
displayed is 0. However, the actual value is that of the
nfs_nrnode tunable. If the tunable is set to a value greater
than 40000, an informational warning is issued at boot
time. Any value greater than 40000 is outside the tested
limit.