Preparation of a snapshot for data storage includes receiving a first command to prepare to create a snapshot of a set of data stored on at least one source storage volume in a data storage system. The data storage system is prepared to expedite creation of the snapshot in response to the first command. A second command to create the snapshot is received subsequent to the first command. The snapshot is created, in response to the second command, by copying the set of data onto at least one target storage volume at an event time. The set of data may comprise a consistency group comprising a set of data blocks, and preparing the system to create the snapshot may include reserving resources, throttling an incoming data rate, starting a timer after receiving the first command, and/or copying data from a plurality of storage volumes into a memory cache.