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CHAPTER 11: NAGIOS INTEGRATION
11.3.4 NUMBER OF SUPPORTED DEVICES
Ultimately the number of devices that can be supported by any particular console server is a function of the number of checks being
made, and how often they are performed. Access method will also play a part. The table below shows the performance of three of the
console server models (1/2-port, 8-port and 16/48 port):
TABLE 11-3. NCSA TESTS
NCSA TESTS
NO ENCRYPTION
3DES
SSH
1 check
~ 0.5 sec
~ 0.5 sec
~ 0.5 sec
100 sequential checks
100.0 sec
100.0 sec
100.0 sec
10 sequential checks, batched upload
1.5 sec
2.0 sec
1.0 sec
100 sequential checks, batched upload
7.0 sec
11.0 sec
6.0 sec
NRPE TESTS
NO ENCRYPTION
3DES
TUNNELED OVER SSH
1 check
0.1 sec
0.3 sec
0.1 sec
10 simultaneous checks
1.0 sec
3.0 sec
1.3 sec
MAX. SIMULTANEOUS CHECKS BEFORE TIMEOUTS
NO ENCRYPTION
3DES
SSH TUNNEL
1-port and 2-port
30
20
25
8-port
30
20
25
16-port and 48-port
30
25
35
The results were from running tests 5 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:
Usually 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 be run
securely without SSL encryption, as SSH will take care of the security.
When the console server submits NSCA results it staggers them over a certain 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 freshness checks will be staggered too.
NSCA checks are also batched. So in the previous example the two checks per minute will be sent through in a single transaction.
