The invention discloses a data disaster tolerant system which is applicable to a wide area network, pertains to the technical filed of computer information storage and solves the problem that the current data disaster tolerant system does not take the effect of data transmission links and the need of lots of redundant data storage space in the wide area network into consideration. The system of the invention comprises M local storage clients connected to the wide area network and N storage servers in different geographical positions; every local storage client consists of a web manager, a snap module, a mapping file redundant array module, a compression module, a decompression module, an encryption module, a decryption module, a backup distribution module and a recovery and integration module; the storage server consists of a failure detection module, a distributed arbitration module, a recovery module, a distributed copy service module, a backup and recovery service module. The system of the invention combines disaster tolerant coding and copying, reduces the amount of redundant data and effectively utilizes storage space. Meanwhile, data to be transmitted is compressed and encrypted, thus improving the safety and reliability of data on network transmission, effectively utilizing network bandwidth and reaching excellent disaster tolerant effect.