How status is computed

This topic explains how the status of an application is computed. The status takes into consideration the severity of each node and thus determines the severity of the entire application. There are two types of algorithms used to compute the status: highest and quorum.

The following is a list of severity types in descending order of severity:

StatusIconDescription
Critical (red)At least one monitored metric exceeded the defined Critical threshold.
Major (dark orange)At least one monitored metric exceeds the defined Major threshold.
Minor (light orange)At least one monitored metric exceeded the defined Minor threshold.
Warning (light orange)At least one monitored metric exceeded the defined Warning threshold.
Information (blue)Information about the item
OK (green)

No monitored metrics exceed the defined thresholds.

Every node in an application model has a status by default. If no events are associated with a node, then the status of the node is OK. If there are events associated with a node, either the highest severity algorithm or the quorum algorithm is used to calculate the status of the node. The highest severity algorithm is used by default.

Highest severity algorithm

By default, the status of every node is calculated using the highest severity algorithm. This algorithm finds the highest severity among all the events associated with a node and assigns that severity as the status of the node.

Algorithm/Formula

Status = Highest severity of impacting events on the node

Quorum Algorithm

The quorum algorithm is applied to calculate the status of a node only when a node is of type cluster or group. Only when a node is marked as group or cluster, can a quorum value be specified for the node. The quorum value is always specified as a percentage value. The quorum algorithm finds the severity of all the nodes in the cluster and uses the following formula to compute the quorum. The status is then computed as the lowest severity among the nodes according to the number derived from the formula.

Algorithm/Formula

Status = Lowest severity among the number of cluster elements with highest statuses

Number of cluster elements with highest statuses = quorum_percent * (Number of hosts /100)

Example

Consider a cluster node comprising 4 hosts: host 1, host 2, host 3, host 4. The severities of the hosts are as follows:

host 1=OK, host 2=OK, host 3=MAJOR, host 4=MINOR

Assume that the quorum percentage is 50.

As per the quorum algorithm, number of cluster elements with highest statuses = quorum_percent * (Number of hosts /100)

That is, number of cluster elements with highest statuses = 50 * (4 /100) = 2

Status = Lowest severity among the number of cluster elements with highest statuses

That is, status = lowest severity among the 2 cluster elements with highest statuses = [host 3=MAJOR, host 4=MINOR]

Status = MINOR

Example for computing severity

The following table lists different scenarios in an application and determines how the status is computed in these scenarios.

NodeTypeClusterStatus propagationQuorumContentsDependent nodesEventsStatusPropagated status =
overall status of dependent nodes

Overall status =
maximum (self, propagated status)

Application 1ApplicationNoN/AN/AN/AServer 1, Server 2NILOKCriticalCRITICAL
Server 1DeviceNoONN/Ahost1Web Cluster, Server 3NILOK - No events associated with itCRITICALCRITICAL
Server 2DeviceNoONN/Ahost2DB Group, Server 41 INFO eventINFO- Max (event severity)MAJORMAJOR
Server 3DeviceNoONNAhost3NIL1 CRITICAL, 2 MAJORCRITICAL - Max (event severity)NA - No dependent nodesCRITICAL
Server 4DeviceNoONNAhost4NIL2 MAJOR, 2 MINORMAJOR - Max (event severity)NA - No dependent nodesMAJOR
Web ClusterGroupYesON50%host5, host6, host7, host8NILhost5 - 2 MAJOR

host6 - 2 INFO

host7 - 2 WARNING, 1 INFO
  
host8 -  1 INFO
INFO

Quorum = Quorum Percentage * No. of Elements/100 = 50*4/100 = 2

In the group of 2 elements with highest status, minimum value is INFO
NA - No dependent nodesINFO
DB GroupGroupNoONNAhost9, host10NILhost 9 - 2 INFO, 1 WARNINGWARNING - Max (event severity)NA - No dependent nodesWARNING

Related topic

Editing application thresholds and configuration details

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