Volume migration among a set of storage systems synchronously replicating a dataset for a volume, where volume migration includes: initiating a transfer of the volume in dependence upon determining that a performance metric for accessing the volume stored on a first storage system would improve if transferred to a second storage system; and during the transfer of the volume: determining status information for the transfer; intercepting an I/O operation directed to the volume; and directing, in dependence upon the status information, the I/O operation to either the first storage system or the second storage system.