The c-tree Server’s mirroring facility makes it possible to create and maintain copies of important files on different drive volumes, partitions or physical drives. If the primary storage location is lost due to some form of catastrophe (i.e., head crash) the mirroring logic can automatically detect the lost connection and switch to the secondary or “mirrored” storage area.
By default, read and write operations on mirrored files will continue without returning an error if one of the files fails, but the other succeeds. When this happens, the failed file is shut down, all subsequent I/O operations continue only with the remaining file and the file name for the shut down file is logged in the server status log, CTSTATUS.FCS.
Both non-transaction controlled and transaction-controlled files can be mirrored. For a transaction controlled file, if a primary and mirror file get out-of-sync beyond the ability of automatic recovery to make them both good, the most up-to-date file is recovered.