Managing NFS and KRPC Kernel Configuration in HP-UX11i v3 (March 2013)

Restrictions on Changing
• The nfs3_max_async_directio_requests tunable is dynamic. System reboot is not required
to activate changes made to this tunable.
• Only NFSv3 TCP mount points that are mounted with forcedirectio options are affected
by changing the value of this tunable.
• This tunable is effective only if nfs3_enable_async_directio_read and/or
nfs3_enable_async_directio_write are enabled
Modifying the Value
The nfs3_max_async_directio_requests tunable works in conjunction with the nfs3_max_transfer_size
tunable and rsize/wsize mount option when determining the mount point transfer bytes.
For example,
if nfs3_max_async_directio_requests is set to 8 and rsize/wsize is set to 32768, the
nfs3_enable_async_directio_read or nfs3_enable_async_directio_write parameters can send or
receive is 8*32768 = 262144 requests in parallel.
Note: If after enabling the nfs3_enable_async_directio_read
or nfs3_enable_async_directio_write parameters, the NFS
client is frequently experiencing NFS READ or WRITE
failures and the system is reporting RPCTIMEOUT error, this
is an indication that the nfs3_max_async_directio_requests
might be set too high. Setting it to a lower value may resolve
this problem.
2.1.27 nfs3_max_threads
Description
The nfs3_max_threads tunable controls the number of kernel threads that perform asynchronous I/O
for NFSv3 filesystems. The operations executed asynchronously are read, readdir, and write.
The nfs2_max_threads tunable controls the number of kernel threads that perform asynchronous I/O
for NFSv2 filesystems. The nfs4_max_threads tunable controls the number of kernel threads that
perform asynchronous I/O for NFSv4 filesystems. For more information on these tunables, see:
• nfs2_max_threads
• nfs4_max_threads
Tested Values
Default: 8
Min: 0
Max: 256