Determine polling
processing requirements
Polling processing is comprised
of a specified number (default 10) of polling threads and several other
threads. The polling threads operate in parallel, while the other threads do
not. The overall polling rate that can be supported is limited by the single
copy threads. If there are many concurrent threads running or if the total
amount of CPU available is not adequate, polling may be adversely affected. A
faster CPU or slower polling rate would be required.
The minimum requirement for
polling is that the total single-threaded polling CPU seconds as specified in
Single-threaded Polling CPU
seconds does not approach the chosen polling interval.
Single-threaded Polling CPU
seconds can be used with the number of managed interfaces and managed
ports obtained or estimated in
Single-threaded Polling CPU
seconds.
Operating system
| IP Availability Manager | IP Availability Manager and
IP Performance Manager (AM-PM)
| ||||
|---|---|---|---|---|---|---|
Per interface
| Per unmanaged port
| Per managed port
| Per interface
| Per unmanaged port
| Per managed port
| |
Linux
| 0.000037
| 0.000000
| 0.000305
| 0.000148
| 0.000000
| 0.001629
|
Solaris
| 0.000222
| 0.000000
| 0.001830
| 0.000888
| 0.000000
| 0.009774
|
Actual SNMP polling is done by
the polling threads; if they are not keeping up due to device latency, more may
be added.
“Calculate SNMP polling thread
utilization” on page 149 will help you determine whether the number of
polling threads needs to be adjusted.
To calculate the total amount of
CPU needed per polling cycle use
Total polling CPU seconds in
conjunction with the number of Managed Interfaces and Managed Ports obtained or
estimated.
Operating system
| IP Availability Manager | IP Availability Manager and
IP Performance Manager (AM-PM)
| ||||
|---|---|---|---|---|---|---|
Per interface
| Per unmanaged port
| Per managed port
| Per interface
| Per unmanaged port
| Per managed port
| |
Linux
| 0.000319
| 0.000000
| 0.001618
| 0.001055
| 0.000000
| 0.011634
|
Solaris
| 0.001914
| 0.000000
| 0.009708
| 0.006330
| 0.000000
| 0.069804
|
While polling will not improve
by increasing the processing power above its minimum requirements, it does have
an absolute requirement for CPU in order to keep up with specified polling
rates. SNMP polling is augmented by pinging all IPs. If the ping fails, the
SNMP requests are suppressed for related interfaces and ports, thus preventing
a sudden influx of timeouts. By default, pinging occurs every 20 seconds. SNMP
polling defaults to every 4 minutes.
The amount of parallelism
possible in the polling subsystem varies, but it is recommended that the total
polling CPU should not exceed 100% of the CPU. This is the effective limit on
how much topology a server can support.
Appendix B, “Hardware
Specifications,” provides specifications of servers measured.