A portion of a nonvolatile memory array that is likely to contain, partially programmed data may be identified from a high sensitivity read, by applying stricter than usual ECC requirements, or using pointers to programmed sectors. The last programmed data may be treated as likely to be partially programmed data. Data in the identified portion may be copied to another location, or left where it is with an indicator to prohibit further programming to the same cells. To avoid compromising previously stored data during subsequent programming, previously stored data may be backed up. Backing up may be done selectively, for example, only for nonsequential data, or only when the previously stored data contains an earlier version of data being programmed. If a backup copy already exists, another backup copy is not created. Sequential commands are treated as a single command if received within a predetermined time period.