My previous blog post says that Cloud-to-Cloud or Hybrid-Cloud would give you the most isolation from just about any issue a CSP could encounter. However, in this particular failure had Availability Zones been available in the South Central region most of the downtime caused by this natural disaster could have been avoided. Microsoft published a Preliminary RCA of the September 4th South Central Outage.
The most important part of that whole summary is as follows…
“Despite onsite redundancies, there are scenarios in which a datacenter cooling failure can impact customer workloads in the affected datacenter.”
What does that mean to you? If your applications all run in the same datacenter you are susceptible to the same type of outage in the future. In Microsoft’s defense, this really shouldn’t be news to you as this has always been true whether you run in Azure, AWS, Google or even your own datacenter. Failure to plan ahead with data replication to a different datacenter and a plan in place to quickly recover your applications in those datacenters in the event of a disaster is simply a lack of planning on your part.
While Microsoft doesn’t publish exact Availability Zone locations, if you believe this map published here you could guess that they are probably anywhere from a 2-10 miles apart from each other.
In all but the most extreme cases, replicating data across Availability Zones should be sufficient for data protection. Some applications such as SQL Server have built in replication technology, but for a broad range of applications, operating systems and data types you will want to investigate block level replication SANless cluster solutions. SANless cluster solutions have traditionally been used for multisite clusters, but the same technology can also be used in the cloud across Availability Zones, Regions, or Hybrid-Cloud for high availability and disaster recovery.
Implementing a SANless cluster that spans Availability Zones, whether it is Azure, AWS or Google, is a pretty simple process given the right tools. Here are a few resources to help get you started.