STeP: Scalable tenant placement for managing database-as-a-service deployments

Public cloud providers with Database-as-a-Service offerings must efficiently allocate computing resources to each of their customers. An effective assignment of tenants both reduces the number of physical servers in use and meets customer expectations at a price point that is competitive in the cloud market. For public cloud vendors like Microsoft and Amazon, this means packing millions of users' databases onto hundreds or thousands of servers. This paper studies tenant placement by examining a publicly released dataset of anonymized customer resource usage statistics from Microsoft's Azure SQL Database production system over a three-month period. We implemented the STeP framework to ingest and analyze this large dataset. STeP allowed us to use this production dataset to evaluate several new algorithms for packing database tenants onto servers. These techniques produce highly efficient packings by collocating tenants with compatible resource usage patterns. The evaluation shows that under a production-sourced customer workload, these techniques are robust to variations in the number of nodes, keeping performance objective violations to a minimum even for high-density tenant packings. In comparison to the algorithm used in production at the time of data collection, our algorithms produce up to 90% fewer performance objective violations and save up to 32% of total operational costs for the cloud provider.