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10. Nagios Integration
To configure additional checks, the downloaded plug-in program must be saved in the tftp addins directory on the USB flash
and the downloaded text plug-in file saved in /etc/config.
To enable these new additional checks, select Serial & Network: Network Port. Select Edit for the network host to be
monitored and New Checks. The additional check option will be included in the updated Nagios Checks list, where you can
again customize the arguments.
10.3.4 Number of Supported Devices
The number of devices that can be supported by a console server is a function of the number of checks being made and how
often they are performed. Access method also plays a role. The table below shows the performance of three console server
models (1/2 port, 8 port and 16/48 port):
Time No encryption 3DES SSH tunnel
NSCA for single check ~ ½ second ~ ½ second ~ ½ second
NSCA for 100 sequential checks 100 seconds 100 seconds 100 seconds
NSCA for 10 sequential checks, batched upload 1 ½ seconds 2 seconds 1 second
NSCA for 100 sequential checks, batched upload 7 seconds 11 seconds 6 seconds
No encryption SSL
no encryption - tunneled over
existing SSH session
NRPE time to service 1 check 1/10th second 1/3rd second 1/8th second
NRPE time to service
10 simultaneous checks
1 second 3 seconds 1 ¼ seconds
Maximum number of simultaneous
checks before timeouts
30
20 (1,2 and 8) or
25 (16 and 48 port)
25 (1,2 and 8 port),
35 (16 and 48 port)
The results were from running tests five times in succession with no timeouts on any runs. However, there are a number of
ways to increase the number of checks you can do:
When using NRPE checks, an individual request will need to set up and tear down an SSL connection. This overhead can be
avoided by setting up an SSH session to the console server and tunneling the NRPE port. This allows the NRPE daemon to run
securely without SSL encryption, as SSH will handle security.
When the console server submits NSCA results, it staggers them over a time period (e.g., 20 checks over 10 minutes will
result in two check results every minute). Staggering the results like this means that in the event of a power failure or other
incident that causes multiple problems, the individual refresh checks will be staggered too.
NSCA checks are also batched. In the previous example, the two checks per minute will be sent through in a single
transaction.
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