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

Modifying the Value
To disable the READDIRPLUS functionality, disable the tunable. Once disabled, the NFS client reverts
to the READDIR operation to retrieve directory contents and the LOOKUP operation to retrieve
extended attributes. For example, if the READDIRPLUS functionality is disabled, commands such as ls
which display only the directory information, can have a shorter response time. Commands such as
find which displays inode numbers and attribute data, can have a longer response time.
If applications require both inode numbers and attribute data, enable the tunable.
2.2.5 nfs3_srv_read_copyavoid
Description
When servicing read requests from NFS clients, the server will make separate copies of the read data
in kernel memory multiple times as part of processing each request. HP recently identified one of these
in-memory copies as being unnecessary, and by eliminating this additional copy the performance of
servicing read requests increases. The nfs3_srv_read_copyavoid tunable controls whether the NFSv3
server will avoid this unnecessary in-memory copy or continue using the standard read logic.
The nfs2_srv_read_copyavoid tunable controls the server-side read copy avoidance feature for NFSv2
filesystems. For more information on this tunable, see nfs2_srv_read_copyavoid.
Tested Values
Default: 0 (Server-side read copy avoidance feature is disabled)
Min: 0
Max: 1 (Server-side read copy avoidance feature is enabled)
Note: Before you enable this tunable, you should install the
Virtual Memory fix (SR: 8606472738) included in patch
PHKL_36457.
Restrictions on Changing
The nfs3_srv_read_copyavoid tunable is dynamic. System reboot is not required to activate changes
made to this tunable. Only NFSv3 mount points are affected by changing the value of this tunable.
Modifying the Value
Enable this tunable to potentially improve the performance of applications that issue read requests in
NFSv3 filesystems.
Warning: Under certain circumstances, enabling the
nfs3_srv_read_copyavoid tunable may cause the following
problems:
– Memory corruption with the message block getting
corrupted (QXCR1000879579)
– Data corruption during READ, when the nfs3_bsize
tunable value is greater than 64 KB
(QXCR1000855994)