Original Research

Downtime Severity Levels (DSL)

A way to measure the Impact and Depth of Downtime in Data Centers — distinguishing inherent and non-inherent downtimes across components, systems, critical rooms, and the full site.

Definition

What are Downtime Severity Levels (DSL)?

Downtime Severity Levels or DSL is a scale that measures the severity of a Data Center downtime according to its impact level. It is designed to be used for Critical Essential Systems.

It is a seven-level scale that classifies the severity of the Data Center downtime according to:

Causes of Downtime: These can be related to Inherent Events (Preventive Maintenance, Failures / CM, Critical Events) or Non-inherent Events (Catastrophic Event, Catastrophic Failure).

Depth of Impact: The location affected by the maintenance/failure or by any other internal/external event related to Structures, Systems, and Components (SSCs).

● DATA CENTER CRITICAL SYSTEMS

Critical Essential Systems are the basis for Data Center Availability

COMPUTER ROOM · DATA ENVIRONMENT · SITE

Electrical System

CRITICAL ESSENTIAL

Cooling System

CRITICAL ESSENTIAL

Telco System

CRITICAL ESSENTIAL

Security

CRITICAL NON-ESSENTIAL

Safety

CRITICAL NON-ESSENTIAL

Critical Essential Systems Provide the minimum necessary to sustain availability. If any Essentials System fails, the service availability will fail imminently.

The 7-Level Scale

DSL and Depth of Impact of Downtime

The DSL was designed as a communication tool, in order to unify and categorize the severity of any event/incident that occurs from a single Component, to a System, Structure, or full Data Center.

DSL Level / Downtime Cause
Downtime Classification
Depth of Impact
DSL 7
Catastrophic Failure
CATASTROPHIC DOWNTIMES
Site Level
DSL 6
Catastrophic Event
CATASTROPHIC DOWNTIMES
Site Level
DSL 5
Critical Downtime
INHERENT DOWNTIMES
Critical Room Level
DSL 4
System Failure / CM
INHERENT DOWNTIMES
System Level
DSL 3
System PM
INHERENT DOWNTIMES
System Level
DSL 2
Component Failure / CM
INHERENT DOWNTIMES
Component Level
DSL 1
Component PM
INHERENT DOWNTIMES
Component Level

    No Downtime = "DSL 0"
  

Catastrophic Events

Can be any hazardous event (fire, fuel spill, etc.) that impacts the Data Center’s normal operations, but has not yet impacted the Critical Room. The downtime is confined to a specific area/systems.

Catastrophic Failures

They are the escalation of a Catastrophic Event impacting the Critical Room (outage).