1. A method, comprising: configuring, by a source storage system, a logical volume to comprise source regions of the source storage system that have a mapping between a host computer and the source storage system, the source regions being physical storage blocks within the logical volume of the source storage system storing source data; wherein the logical volume is stored across multiple storage devices in a respective storage controller; at a first time, copying the source data from the source regions to target data in target regions of a target storage system, the target regions comprising physical blocks within a logical volume of the target storage system and being in a one-to-one correspondence with the source regions; wherein the source regions and the target regions each comprise a partition having a sequence of bytes of a specific length of 1 Megabyte (MB), the sequence of bytes corresponding to a beginning block and ending block of the source data within the logical volume copied from the source regions to the target regions such that only the sequence of bytes comprising the partition of the specific length are copied; reconfiguring the logical volume so that the target regions have the mapping between the host computer and the source storage system, such that input/output (I/O) requests are proxied through the source storage system to the target storage system; receiving, by the source storage system, a request to store an update to the one of the source regions, storing the update to the one of the source regions, and storing the update to the proxied corresponding target region; and at a second time, copying attributes and run-time information for the logical volume from the source storage system to the target storage system, and deleting the source data from the source storage system while maintaining the mapping between the host computer and the source storage system, wherein the attributes comprise a serial number and a read-only status, and wherein the run-time information comprises a reservation and login information.