  Today, companies and data centers are moving towards cloud and serverless
storage systems instead of traditional file systems. As a result of such a
transition, allocating sufficient resources to users and parties to satisfy
their service level demands has become crucial in cloud storage. In cloud
storage, the schedulability of system components and requests is of great
importance to achieving QoS goals. However, the bufferbloat phenomenon in
storage backends impacts the schedulability of the system. In a storage server,
bufferbloat happens when the server submits all requests immediately to the
storage backend due to a large buffer in the backend. In recent decades, many
studies have focused on the bufferbloat as a latency problem. Nevertheless,
none of these works investigate the impact of bufferbloat on the schedulability
of the system. In this paper, we demonstrate that the bufferbloat impacts
scheduling and performance isolation and identify utilizing admission control
in the storage backend as an easy-to-adopt solution to mitigate bufferbloat.
Moreover, we show that traditional static admission controls are inadequate in
the face of dynamic workloads in cloud environments. Finally, we propose
SlowFast CoDel, an adaptive admission control, as a starting point for
developing adaptive admission control mechanisms to mitigate bufferbloat in
cloud storage.
