An illustrative method includes receiving a write request to write payload data to a virtual storage volume; transmitting the write request to a plurality of storage nodes each storing a replica of the virtual storage volume; acknowledging the write request only after a quorum of the storage nodes has stored the payload in their respective kernel memory; and flushing the payloads stored in each kernel memory to persistent storage only after a threshold number of outstanding write requests that have been acknowledged, but not yet flushed, has been reached, the flushing configured to optimize performance for synchronous workloads.