1. A computer-implemented method comprising: receiving, at a first node of a plurality of nodes in a cluster, an allocation request for space in a replication log, wherein the first node is configured to receive the allocation request from a second node of the plurality of nodes, and the replication log stores information describing one or more outstanding write operations; in response to receiving the allocation request, determining an amount of storage to allocate in the replication log, wherein the determining is based, at least in part, on one or more parameters, and the one or more parameters comprise at least one of a backlog capacity of the second node, or a scheduling priority for a data volume; and allocating the amount of storage in the replication log.