Arguing that complete, reliable, up-to-date system documentation is critical for every data processing environment, this paper on computer disaster recovery planning begins by discussing the importance of such documentation both for recovering from a systems crash, and for system maintenance and enhancement. The various components of system documentation are then explained, followed by descriptions of the three stages of creation of complete system documentation: (1) design and development documentation; (2) backup documentation; and (3) documentation reports. Environmental controls, a second major aspect of disaster recovery planning, are then discussed, with emphasis on problems with the electrical power supply such as "blinks,""brownouts," and "blackouts." Ways to ensure an uninterruptable power supply, voltage tolerance of the computer's chart, and sources of assistance are also considered. A discussion of safeguards that can be used to protect the data processing system, including various kinds of insurance, concludes the paper. (RP)