[lefrancaiz]

>The sharding project bought us some time regarding database capacity, but as we soon found out, there was a huge single point of failure in our infrastructure. All those shards were still using a single Redis. At one point, the outage of that Redis took down all of Shopify, causing a major disruption we later called “Redismageddon”. This taught us an important lesson to avoid any resources that are shared across all of Shopify.

It seems that it does happen sometimes, however.

https://shopify.engineering/e-commerce-at-scale-inside-shopi...