The present invention relates to a handheld radiotelephone having a battery pack attachably and detachably equipped on a rear surface of a main body, and a locking device for allowing the battery pack to be attached or detached. The method first provides extraction parameter sets, wherein the extraction parameter sets comprise a first extraction parameter set and a second extraction parameter set. This data can be migrated from a source virtual machine to a target virtual machine by sending the immutable data along with the low volatility data first\u2014before the source virtual machine has stopped itself for the migration process.