How Sam Scans An Instance - NEC Express5800/320Ma User Manual

How SAM Scans an Instance

SAM scans the instance at the Scan poll rate (for example, every 30 seconds). If it finds
a threshold violation, it checks Scan retry and Number of scan retries.
If Scan retry and (therefore) Number of scan retries are disabled, SAM issues an alert.
(Therefore, if you disable Number of scan retries, a single threshold violation generates
an alert condition.)
If SAM finds a threshold violation and Scan retry and Number of scan retries are
enabled, SAM starts rescanning the instance:
•
For the number of times specified by the Number of scan retries value.
•
At the interval specified by Scan retry poll rate values.
Number of scan retries specifies how many times SAM will rescan the instance. Scan
retry poll rate specifies the interval, in seconds, at which SAM rescans after detecting
the first threshold violation. Subsequent scans are used to verify that the threshold
violation was not temporary (a spike).
For example, given a Number of scan retries value of 3, if SAM detects 3 more
threshold violations (after the first one it detected), the violation was not temporary, and
SAM generates an alert.
If, on the other hand, SAM detects fewer than 3 more violations, the threshold violation
was temporary. In other words, whenever a rescan detects that a parameter has
returned to within its normal range of values, SAM interprets the violation as temporary
and returns to scanning according to Scan poll rate (in seconds).
After SAM generates an alert, it then checks whether the Time between alerts
parameter is enabled. If it is, SAM resumes scans at the Scan poll rate but will not
generate another alert until the Time between alerts expires. If Time between alerts is
not enabled, SAM resumes scans at the Scan poll rate and will continue to generate
an alert based on the retry and re-alert sequence described above.
There are two additional conditions that apply to the preceding sequences. First, if SAM
detects a more-severe threshold violation (that is, a change from a Warning to an
Alarm), it restarts scanning the instance at the Scan poll rate, as described at the
beginning of this section. Second, if the alert condition returns to a normal value (that
is, within all thresholds), SAM sends the Return to Normal message; either the default
message or the one you configured in the Return to Normal Message Body. (See
"Email Alert Setup" on page 3-3
message.)
for information about setting up the Return to Normal
How SAM Scans an Instance
SAM Settings Reference 2-7