iTP Secure WebServer System Administrator's Guide (iTPWebSvr 5.1+)

Installing the iTP Secure WebServer
iTP Secure WebServer System Administrator’s Guide—522659-001
2-4
Preparing Your System for the iTP Secure
WebServer
Use One TCPSAM Process
Ensure that there is one TCPSAM process pair running on any two CPUs in the
system. It is recommended that you use only one TCPSAM process pair - even
where you are using more than one IP address. Unlike the conventional TCP/IP
processes, one TCPSAM process can provide socket interfaces for all IP addresses
configured in the Parallel Library TCP/IP environment. If you use more than one,
two httpd servers may attempt access to the same port and therefore generate
EADDRINUSE socket errors.
Use Static Servers
It is strongly recommended that you run as many static servers as you may need.
Again, this is not new information. Creating dynamic servers is known to be
expensive and will severely affect response time - especially for the request waiting
for the dynamic server to be created. In addition, dynamic servers may drop one or
two connections when the Deletedelay effect occurs. Because all of the httpd servers
are designed to run on high pin, creating more servers at the startup should not
create a resource problem.
Specify a Larger Tandem_Receive_Depth
The range is 1 to 255. The default is 50. Selecting a larger number will prevent extra
pathsends and possible socket migration. When the connection request is sent to a
server that is not running on the same CPU as the original listening agent, a socket
migration will occur and a performance penalty is incurred. A larger number will
also prevent the creation of dynamic servers. Creating an additional httpd server on a
CPU that already has a number of httpd servers running is neither going to help
distribute the load nor improve performance. Note that now load distribution has
been moved down to the adapter level by use of the round-robin filter. Additional
processes may create more dispatching costs for the CPU.
Specify the -address Command in All Accept Directives
It is also recommended to use the -address command in all Accept directives. Unlike
the conventional TCP/IP processes TCPSAM allows the httpd servers to interface
with all subnets configured in the Parallel Library TCP/IP environment. The “accept
ALL IP addresses” is literally ALL IP addresses defined in the entire system. This
may be more than you expected.
Rebalancing Servers Across CPUs
When a CPU is brought down, PATHMON is likely to restart a number of static
servers on other CPUs in order to keep the number of static servers as specified in
the NUMSTATIC server attribute. When the CPU is reloaded, PATHMON will not
automatically rebalance its servers among the CPUs. If there are extensive reloads
you may want to rebalance manually - using actions ranging from a simple stopping
of one or two servers, to a complete restart of the iTPWebServer. Again, this
behavior is not new to the PATHWAY system, it just may be more obvious when
everything from application to transport is vertically aligned.