Libservices: dynamic storage provisioning for multitenant I/O isolation.

Containers are commonly used to run the data-intensive applications of different tenants in cloud infrastructures. The storage I/O of the colocated tenants is typically handled by the shared system kernel of the container host. When a data-intensive container competes with a noisy neighbor, the kernel I/O services can cause performance variability and slowdown. This is a challenging problem for which several approaches have already been explored. Although the dynamic resource allocation, kernel structure replication, and hardware-level virtualization are helpful, they incur costs of high implementation complexity and execution overhead. As a realistic cost-effective alternative, we isolate the I/O path of each tenant by running dedicated storage systems at user level on reserved resources. We introduce the libservices as a unified user-level storage abstraction to dynamically provision per tenant container root filesystems, application data filesystems and image repositories. We outline several examples of container storage systems whose clients and servers can be composed from libservices. With an early prototype, we successfully demonstrate that the libservices combine the required efficiency and flexibility to build isolated I/O services on multitenant hosts with superior performance over existing user-level or kernel-level systems.