Automatic centralized monitoring system
Automatic fault detection and recovery system which provides stability and continuity of operation in an industrial multiprocessor control
Data compression process
High speed data compression and decompression apparatus and method
System memory for a reduction processor evaluating programs stored as binary directed graphs employing variable-free applicative language codes
Method for communicating changes made to text form a text processor to a remote host
Memory back-up system
Database backup method
ApplicationNo. 757134 filed on 12/03/1996
US Classes:707/204, Archiving or backup707/10, Distributed or remote access707/202, Recoverability711/111, Accessing dynamic storage device711/162, Backup714/6Redundant stored data accessed (e.g., duplicated data, error correction coded data, or other parity-type data)
ExaminersPrimary: Amsbury, Wayne
Assistant: Pardo, Thuy N.
Attorney, Agent or Firm
Foreign Patent References
International ClassG06F 017/00
AbstractA system backs up computer files to a remote site via modem. Files of a user computer that are found in a common library at the remote site initially are not copied to the remote site, whereas files not in the library are copied to the remote site. Then, periodically the user computer determines which blocks have been changed, and the user computer transmits only changed blocks to the remote site. The blocks are gathered in "chunk" files, and when a chunk file reaches a predetermined size, it is transmitted to the remote site for updating the back up version of the respective file. The process then resumes identifying changed blocks. In addition to flagging the changed block for transfer, the process resynchronizes the local data file with the backed up version using a two-step comparison, first comparing the first two characters in the block with a pre-stored character set, and then, if the first comparison results in a match, comparing a digital signature of the changed block with a pre-stored signature. If either comparison results in a mismatch, the test is repeated using, as the first byte of the test block, the next byte in the sequence.