This function synchronizes the running database to disk and starts an asyncrynous backup (Genesis copies the files to the file binary.bak, where binary is the binary database directory name specified upon bootup). This function executes atomically, and a slight pause may be noticed while it synchronizes the object cache to disk and copies the index files.
The return value of backup() is always 1, and should be ignored. If a backup is in progress the error ~perm is thrown. The error ~file is thrown if there are file or directory problems. When the asyncrynous backup is finished the driver calls $sys.backup_done().
backup() | set_heartbeat() | shutdown() | anticipate_assignment() | config() | cache_info()