I/o scheduling and load balancing across the multiple nodes of a clustered environment utilizing data volume based scheduling priorities

Abstract

Write operations are scheduled for multiple nodes in a shared storage cluster that supports volume replication. Requests are received from nodes for allocation of space for write operations in a replication log. In response to a received request, the current capacity of the requesting node to manage a backlog can be determined. The amount of space in the replication log allocated to the node is then calibrated to the node's capacity, thereby preventing self-throttling. A separate priority can be assigned to each volume, and space in the replication log assigned to each volume based on its priority. Nodes can target synchronous and other latency sensitive operations to higher priority volumes. A single global queue can be maintained to schedule write operations for all nodes, thereby providing a fair scheduling. A separate local queue can be maintained for each node, thereby providing specific levels of preference to specific nodes.