Atlassian migrated approximately 4 million Jira databases to Amazon Aurora to enhance the reliability and cost-effectiveness of its Jira Cloud platform. The migration involved 2,403 RDS database instances, resulting in 2.6 million databases migrated and 1.8 million databases drained from source instances. Each Jira database corresponds to about 5,000 files on disk, leading to over 27.4 billion total database files utilized in Jira. The migration aimed for a service level agreement (SLA) of 99.99% and involved technical challenges due to the large number of databases and files. At its peak, Atlassian migrated up to 90,000 Jira databases daily, averaging around 38,000 databases per day. The team developed a custom orchestration tool and utilized AWS Step Functions to manage the migration process while minimizing tenant downtime and migration expenses.