Monitoring standard deviation parameters
BMC PATROL for Internet Servers includes a set of parameters that report standard deviation statistical metrics. Standard deviation reflects how likely or unlikely it is that a performance metric is normal in your environment.
Generally, if the standard deviation parameters follow normal rules of probability, 68.3% of the data for any given collection cycle should fall within a standard deviation of less than 1, while more than 95 percent of values are expected to fall within 2. All but the most unusual surges should fall within 3 standard deviations of normal. To prevent occasional peaks from setting off alarms, the standard deviation parameters do not trigger alarms unless the deviation persists over three consecutive cycles.
By default, these parameters are enabled and their values calculated, but their alarms are inactive. If you wish to set alarms on standard deviation parameters, a reasonable starting point is 2 to 3 on Alarm 1 and 3 to 10 on Alarm 2, and if those values generate spurious alarms, set them a notch higher: 3 to 4 on Alarm 1 and 4 to 10 on Alarm 2.
To enable or disable standard deviation parameters
- From the INET_Services icon, select the KM Command Std Deviation Params.
A dialog will ask you if you want to enable (or disable, if already active) the standard deviation parameters. - Click Accept to change the status to enabled (or disabled, if already active). Click Cancel to leave the parameters disabled (or enabled).
The following standard deviation parameters are provided:
- dnsCheckResponseTimeStdDev
- ftpResponseTimeStdDeviation
- httpResponseTimeStdDeviation
- imapResponseTimeStdDeviation
- ldapResponseTimeStdDeviation
- nntpResponseTimeStdDeviation
- pageResponseTimeStdDeviation
- pop3ResponseTimeStdDeviation
- portResponseTimeStdDeviation
- requestRateStdDeviation
- remoteDnsResponseTimeStdDev
- smtpResponseTimeStdDeviation
All standard deviation parameters are toggled on or off simultaneously. See the Online Help for details. See Monitor-types-and-attributes.