Interesting that you are asking for the dirt given that DiRT stands for Disaster and Recovery Testing, at least at Google.
Every year there is a DiRT week where hundreds of tests are run. That obviously requires a ton of planning that starts well in advance. The objective is, of course, that despite all the testing nobody outside Google notices anything special. Given the volume and intrusiveness of these tests, the DiRT team is doing quite an impressive job.
While the DiRT week is the most intense testing period, disaster preparedness is not limited to just one event per year. There are also plenty tests conducted througout the year, some planned centrally, some done by individual teams. That's in addition to the regular training and exercises that SRE teams are doing periodically.
Every year there is a DiRT week where hundreds of tests are run. That obviously requires a ton of planning that starts well in advance. The objective is, of course, that despite all the testing nobody outside Google notices anything special. Given the volume and intrusiveness of these tests, the DiRT team is doing quite an impressive job.
While the DiRT week is the most intense testing period, disaster preparedness is not limited to just one event per year. There are also plenty tests conducted througout the year, some planned centrally, some done by individual teams. That's in addition to the regular training and exercises that SRE teams are doing periodically.
If you are interested in reading more about Google's approach to distaster planning and preparedness, you may be interested in reading the DiRT, or how to get dirty section from Shrinking the time to mitigate production incidents—CRE life lessons (https://cloud.google.com/blog/products/management-tools/shri...) and Weathering the Unexpected (https://queue.acm.org/detail.cfm?id=2371516).