Customer data was irretrievably lost in one of three AWS availability zones in the United Arab Emirates region, specifically the mec1-az2 availability zone. Each availability zone is serviced by one or more Amazon data centers.

For those that are not regulars in enterprise cloud computing architecture, it is a known pattern that any critical data should exist in at least two availability zones (AZ). The assumption is that you should be able to lose and entire AZ and still be able to bring up your services again without significant loss of data.

But the destruction was apparently even more widespread for the data centers in the Bahrain region, because Amazon said it was unable to restore access to resources and data across all three availability zones there. “The damage to our infrastructure spanned multiple Availability Zones and exceeded what our regional and multi-AZ services are designed to withstand,” the AWS update said.

In this AWS region, even the general best practices didn't protect services/data. Usually only really important applications/services are designed to withstand multi-region failure, which is what this is for the AWS Bahrain region (me-south-1).