Technologies are provided herein for asynchronous data replication. A primary server maintains and exposes a storage volume for use by storage clients. The primary server receives write operations directed toward the storage volume and performs the writes on the storage volume. The primary server also creates buckets containing each of the write operations. The buckets are opened at a first point in time and closed at a second point in time that may be selected based upon the contents of the buckets, a predefined time period, or based upon an indication from an application program. The buckets are transmitted to a second server computer asynchronously. When each bucket is received completely by the second server, its contents are written to a storage volume maintained by the second computer. The buckets may be created from pages of a write-back cache utilizing a zero buffer copy mechanism.