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Tuning Techniques

2.3 Solving Performance Problems

• Apply any patches recommended for your operating system.

See the Recommended Patch Table for information about operating system

patches that can improve performance.

• Apply the kernel attribute values that are recommended for your type of

system.

See Section 2.3.1 for a list of attributes that can be tuned to improve

performance.

• Prevent ‘‘forbidden’’ and ‘‘url could not load’’ messages on Netscape enterprise

server systems.

2.3.1 Tuning Recommendations for a Primary Server

This section provides recommendations for tuning a server for optimal

performance. These recommendations are applicable to most conﬁgurations

and include the attribute value and a reference to additional information.

The primary recommendations for servers, (including web servers, proxy servers,

gateway systems, and ﬁrewall systems) are as follows:

• Tune the following

socket

subsystem attributes:

somaxconn = 65535

sominconn = 65535

• Tune the following

inet

subsystem attributes:

pmtu_enabled = 0

For proxy servers, gateway systems, and ﬁrewall systems, also apply these

additional recommendations:

• Modify the following socket subsystem attribute as follows:

sbcompress_threshold = 600

• Modify the following

inet

subsystem attribute as follows:

ipport_userreserved = 65000

2.3.2 Improving Gigabit Ethernet Performance

You can improve the performance of TCP/IP Services over Gigabit Ethernet (GbE)

by conﬁguring the system to use jumbo frames.

Jumbo frames (frames larger than the 1518 octets speciﬁed by the IEEE 802.3

standard) improve performance because more data can be transmitted in each

frame, hence reducing the frame rate and interrupt load on a system. Jumbo

frames must be conﬁgured on both the Gigabit Ethernet switch as well as the

Gigabit Ethernet controllers on the host systems. Conﬁgure jumbo frames before

you start TCP/IP Services on the OpenVMS server.

There are two ways to conﬁgure jumbo frames for Gigabit Ethernet controllers on

OpenVMS:

• Including the following LANCP command in SYSTARTUP_VMS.COM:

$ mcr lancp set dev ewa/jumbo ! enable jumbo frames for GbE.

• Setting the SYSGEN parameter LAN_FLAGS in MODPARAMS.DAT and

running AUTOGEN. For example:

LAN_FLAGS=64 ! Set bit 6 to enable jumbo frames on GbE, a dynamic parameter

2–18 Tuning Techniques