Introduction
When we talk about “the cloud,” it’s easy to forget that underneath all the layers of abstraction, cloud servers exist on physical hardware, in physical building. And yes, like any physical system, they can and do crash.
Cloud servers and VPS’ are not immune to failures. Every virtual machine, docker container and microservice runs on actual computers with processors, memory, storage, and power supplies—all of which can malfunction. Whether you’re using AWS, Google Cloud, Azure, or the budget provider your boss shoved down your throat, your workloads ultimately run on real servers in data centers that face the same fundamental limitations as any computer.
That said, as cloud providers we go to extraordinary lengths to minimize the impact of these inevitable failures.
Highly Redundant Data Centers
Modern cloud data centers are engineering marvels designed with redundancy at every level, including:
- Multiple power feeds and backup generators
- Redundant cooling systems
- Geographically distributed locations to protect against regional disasters
- Network path diversity to prevent connectivity issues
At the extreme end of these design principles is Tier IV data centers. Certified by Uptime Institute, these facilities incorporate as much redundancy as they can to make sure systems stay online.
You can check out data center certifications here.
Reliable Hardware
While cloud providers invest in highly redundant hardware, such as dual power supply chassis’, ECC memory, RAID or other types of redundant storage, hot-swappable components, and redundant network infrastructure to house your cloud servers, the amount of data they collect to make these decisions isn’t always obvious.
While the majority of this data is kept private by providers, there are some published examples like Backblaze’s drive failure statistics that give us an insight into how cloud providers make decisions on the hardware they run.
Resilient Software Stacks
From the hypervisor running the cloud infrastructure, to the operating system and software running within your cloud server, you can gain a lot of reliability from the correct software stack. Some considerations include:
- Highly available storage – SANs are a tried and true medium for resilient storage, but over the last decade we’ve seen the emergence of distributed file systems, such as Ceph, GlusterFS, and vSAN, which bring their own spin on things.
- Live Migration – Mostly a standard feature now, the ability to move a cloud server between physical hosts without downtime allows server maintenance to happen without interruption to workloads.
- Monitoring and Observability – Accurate and timely data is key to maintaining functional infrastructure, and cloud providers need to maintain the best systems they can so they can respond and even predict hardware issues.
- Automated Recovery – Most modern hypervisors offer some form of HA, like VMWare HA or Openstack’s Masakari for automatic failover of VM’s when there is a hardware issue.
Highly Available Solutions
All of the above said, there is a limit to how far you can rely on your cloud server provider. For applications that cannot tolerate downtime, cloud environments enable engineered high-availability solutions:
- Load balancing across multiple servers
- Automatic scaling mechanisms
- Multi-region deployments
- Containerized applications that can quickly restart on healthy infrastructure
These approaches ensure that even when individual servers crash (which they will), your services remain available and responsive.
The truth is that cloud servers aren’t magical. Yes, they can be sophisticated systems, but they are still built on physical hardware with inherent limitations. The real magic lies in how cloud providers and architects anticipate and accommodate these limitations.