Tuning HP Tru64 UNIX V5.1A and V5.1B for Oracle

max_async_req

HP recommends setting this tunable parameter to at least 256.

Note: As of Tru64 UNIX V5.1B-2 (PK4) Service PAK, the default value for this parameter has been

raised to 1000.

max_sessions

HP recommends setting this tunable parameter to at least the number of Oracle processes plus 2.

rdg_max_auto_msg_wires

HP recommends setting this tunable parameter to 0.

RM Subsystem

Due to an oversight, the Oracle 9i RAC installation guide states that the value for the

rm_check_for_ipl parameter must be set to 0. This is no longer true. rm_check_for_ipl

should be left at its default value. Make sure that this parameter is not changed in the

/etc/sysconfigtab file.

Improving the Performance of gettimeofday() in Oracle

The Oracle server times many functions as it executes; this is especially true if the init.ora

parameter timed_statistics is set to TRUE.

These timing functions result in system calls into the operating system kernel, which can degrade

Oracle performance because the calling process relinquishes the CPU. There is a feature in Tru64

UNIX that gives a process direct access to the operating system's real-time clock.

Using this feature will improve performance on a heavily used system; it will also improve

performance on a lightly loaded system but it may not be as noticeable.

To enable this feature, enter the following command sequence with root privileges:

mknod /dev/timedev c 15 0

chmod 644 /dev/timedev

The previous commands only have to be performed once for each system or node in a cluster. The

/dev/timedev device special file will be persistent across system reboots. In order to use this

feature with Oracle the instance has to be restarted. The existence of /dev/timedev is checked only

on instance startup.

It is recommended that all instances in a TruCluster Server environment (and hence all nodes) have

this feature enabled. This feature is supported on Oracle version 7.3 and later.

Oracle has made further optimizations to this in the latest versions of Oracle 9 and Oracle 10 by

using a newer version of the times(3) system call. These versions of Oracle require that an ERP be

installed that implements the changed system-call. Seethe Tru64 UNIX/TruCluster Server V5.1B-2 with

PK4 Service PAK for V5.1B-2 section and Tru64 UNIX/TruCluster Server V5.1A with PK6 Service PAK

for V5.1A PK6 section for more information.

Selecting IPC Communication Protocols for Oracle RAC

Oracle can use either User Datagram Protocol (UDP) or Reliable Datagram (RDG) for DLM/IPQ inter-

instance communication. Starting with Oracle 9i, HP recommends using RDG as the protocol for IPC

instead of using UDP.

RDG communication is recommended for Oracle 9i Real Application Clusters (RAC) and later.