Updated on October 17, 2024

October 17, 2024

Incident severity levels explained

Incidents happen and sooner or later your company will experience one too. To discover them sooner, we have to measure uptime and monitor servers.

What is incident severity?

Incident severity refers to the level of impact an incident has on the organization, its customers, and its operations. The extent of the disruption typically measures severity, the number of users affected, and the potential financial impact. Incident severity is usually categorized into three to five levels, with Level 1 being the most severe and Level 5 being the least severe.

Incident severity levels

Here are some typical incident severity levels:

  • Level 0 (Critical): A critical incident that has a significant impact on the organization, its customers, or its operations. Examples include a complete system outage, a major security breach, or a critical data loss that affects multiple customers.
  • Level 1 (High): A high-severity incident that has a moderate impact on the organization, its customers, or its operations. Examples include a partial system outage that affects a single department, a minor security breach that requires immediate attention, or a significant data loss that requires restoration from backups.
  • Level 2 (Medium): A medium-severity incident that has a limited impact on the organization, its customers, or its operations. Examples include a minor system outage that affects a small group of users, a non-critical data loss that can be easily recovered, or a minor security breach that requires minimal remediation.
  • Level 3 (Low): A low-severity incident that has a minimal impact on the organization, its customers, or its operations. Examples include a minor issue with a non-critical system that can be resolved quickly such as latency, a minor data loss that has no significant impact, or a minor security breach that requires minimal attention.
  • Level 4 (Informational): An informational incident that has no significant impact on the organization, its customers, or its operations. Examples include routine system maintenance, a minor software update, or a minor configuration change that requires no immediate attention.

What is the difference between P0, SEV0 and Critical severity?

Different organizations and industries use various notations to represent incident severity levels. Some common notations include:

  • P1, P2, P3, etc.: This notation is commonly used in IT service management, where P1 represents the highest severity and P5 represents the lowest.
  • SEV0, SEV1, SEV2, etc.: This notation is often used in software development and IT operations, where SEV0 represents the highest severity and SEV5 represents the lowest.
  • High, Medium, Low: This notation is simple and easy to understand, with High representing the most severe incidents and Low representing the least severe.
  • Critical, Major, Minor: This notation is often used in business continuity and disaster recovery planning, where Critical represents the most severe incidents and Minor represents the least severe.

These notations can be used interchangeably, and the specific notation used may depend on your organization's incident management process and the industry you work in.

Incident priority vs. severity

While incident severity measures the impact of an incident, incident priority refers to the incident's urgency. Priority is typically determined by the incident's severity, the number of users affected, and the potential business impact.

Using an incident severity matrix

An incident matrix is a useful tool that can help you categorize and prioritize incidents effectively. An incident matrix is a table that maps incident severity levels against incident priority levels providing a way to determine the severity and priority of an incident.