The main cause of data center outages are power failures, followed by human errors, software and cyber attacks, cooling failures and even third party/network failures.
Although data centers do have batteries and backup generators, power failures are considered the leading cause of data center outages and account for around 45 percent of significant data center outages, with the UPS or uninterruptible power supply failures being the most common cause.
UPS failures, generator failures and utility grid issues are the main causes of downtime with data centers.
Human errors like accidental disconnection, failures in following procedures and misconfiguration also frequently cause data center outages.
Software and Cyber attacks are fast growing causes of data center outages, which include ransomware and DDoS attacks and inadequate cooling leads to overheating, especially with high density AI servers.
And failures in hosting providers or network infrastructure also cause data center outages.
In May of 2026, a major AWS Amazon data center outage in North Virginia was triggered by a rapid temperature spike and subsequent power failure.
Data centers rarely go down completely as data centers have backup generators, as well as batteries to keep the data center up and servers line.
Although around 50 to 55 percent of data centers experience any impactful outage over a 3 year period.
In the event of a power outage, data centers have batteries that keep the servers online, while the generators are able to start and take over the load.
So as long as the generators for the data center have enough fuel the data center can remain powered on and operating without any issues.
Most often when a data center has an outage, it's usually a network outage, which could be with one or more of the data center's routers or even a backbone internet router that connects the data center with the rest of the world.
Over half of data centers though do experience some impactful outage in any 3 year period.
And although frequent, the overall outage frequency of data centers and the severity of the data center outage are declining.
Common causes of data center outages include power failures, which are the top 36 percent cause of data center outages, followed by cooling failures, software errors and network issues.
A 3rd of the data center outages also cost more than $250,000.00 in downtime, with many exceeding $1 million in damages.
Typical uptime tiers and availability goes for data centers includes.
Tier 1 (Basic) 2.8 hours annual downtime or 99.671% uptime.
Tier 3 (Concurrent Maintainable) 1.6 hours annual downtime or 99.982% uptime.
And Tier 4 (Fault Tolerant) 26.3 minutes of annual downtime or 99.995% uptime.
No matter how good a data center or even web host is, all data centers and web hosting companies are prone to some downtime.
But data centers are usually up most of the time.