The Stromos was one of three ships built by the people of Talthus to preserve their race when a dark star threatened the destruction of their world. The Stromos was intended to carry over one thousand chosen survivors to the new homeworld of Ardena. A lottery was held to select the passengers, and among those aboard the ship were Martice, the sovereign of Talthus, Tryan, the ship's engineer, and Officer Pharrin and his young son Keenin. Because of the vast distance between Talthus and Ardena, the journey without faster-than-light technology would take hundreds of years. Therefore the ship held hundreds of cryogenic chambers to carry the passengers in stasis.
A person undertaking such a long journey without proper storage of his consciousness would arrive at the destination with significant loss of memory and intellect, and his very essence would be lost. For this reason, the consciousness must be separated from the body. Each cryogenic capsule contains an active matrix module sufficient to sustain one single mind, and each cryosleeper's consciousness is stored in the same memory module that regulates and sustains the corresponding sleeper's body. There are failsafes to prevent one from returning to any other body than one's own, and there is no way to separate the memory and body or to send the consciousness to any other than its corresponding body, unless the sleepers' bodies are dead. Only then can the failsafes be overridden and the consciousness purged from the system.
However, when the Stromos crashed on P2A-347, Pharrin was revived by the computer as the drain on the ship's power caused the cryogenic compartments to fail. In a desperate attempt to save the last of his people, Pharrin overrode the failsafes and took twelve other souls into his own body, then rendered SG-1 unconscious and downloaded another dozen souls into Daniel. In exchange for the restoration of Daniel, SG-1 promised to save the last of Pharrin's race. They used a naquadah generator to sustain the power of the Stromos, making it possible to restore and revive the other passengers and to relocate them to a new homeworld through the stargate.
Episode Reference: Lifeboat