Monzo’s 2019 Cassandra Outage

After 10 post-mortems in their first season, Tom and Jamie reflect on the common issues they’ve seen. Click through for details! Summing Up Downtime We’re just about through our inaugural season of The Downtime Project podcast, and to celebrate, we’re reflecting back on recurring themes we’ve noticed in many of the ten outages we’ve poured […]

On May 11, 2021, Salesforce had a multi hour outage that affected numerous services.  Their public writeup was somewhat controversial — it’s the first one we’ve done on this show that called out the actions of a single individual in a negative light. The latest SRE Weekly has a good list of some different articles […]

During a routine addition of some servers to the Kinesis front end cluster in US-East-1 in November 2020, AWS ran into an OS limit on the max number of threads. That resulted in a multi hour outage that affected a number of other AWS servers, including ECS, EKS, Cognito, and Cloudwatch. We probably won’t do […]

In November 2020, Coinbase had a problem while rotating their internal TLS certificates and accidentally unleashed a huge amount of traffic on some internal services. This was a refreshingly non-database related incident that led to an interesting discussion about the future of infrastructure as code, the limits of human code review, and how many load […]

Just one day after we released Episode 5 about Auth0’s 2018 outage, Auth0 suffered a 4 hour, 20 minute outage that was caused by a combination of several large queries and a series of database cache misses.  This was a very serious outage, as many users were unable to log in to sites across the […]

Tom was feeling under the weather after joining Team Pfizer last week, so today we have a special guest episode with Sujay Jayakar, Jamie’s co-founder and engineer extraordinaire. While it’s great to respond well to an outage, it’s even better to design and test systems in such a way that outages don’t happen. As we […]

In 2018, after 43 seconds of connectivity issues between their East and West coast datacenters and a rapid promotion of a new primary, GitHub ended up with unique data written to two different databases. As detailed in the postmortem, this resulted in 24 hours of degraded service. This episode spends a lot of time on […]

Auth0 experienced multiple hours of degraded performance and increased error rates in November of 2018 after several unexpected events, including a migration that dropped some indexes from their database. The published post-mortem has a full timeline and a great list of action items, though it is curiously missing a few details, like exactly what database […]

On July 2, 2019, a subtle issue in a regular expression took down Cloudflare (and with it, a large portion of the internet) for 30 minutes.

Monzo experienced some issues while adding servers to their Cassandra cluster on July 29th, 2019. Thanks to some good practices, the team recovered quickly and no data was permanently lost.