System and method for backing up computer files over a wide area computer network

• US 6,049,874 A
• Filed: 03/12/1998
• Issued: 04/11/2000
• Est. Priority Date: 12/03/1996
• Status: Expired due to Term

• Current Assignee: CDD Technologies LLC (IPNav)
• Original Assignee: Fairbanks Systems Group
• Inventors: McClain, Fred W., Bolt, Thomas B.
• Primary Examiner(s): Swann, Tod R.
• Assistant Examiner(s): CODDINGTON, TREVOR Q
• Application Number:
  US09/041,149
• Time in Patent Office: 761 Days
• Field of Search: 711/161, 711/162, 707/204, 713/200, 380/4
• US Class Current: 713/176
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1461 Backup scheduling policy
• CPC Class Codes: G06Q 40/08 Insurance
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

A system backs up computer files to a remote site via modem, LAN, WAN, or other network device 16. 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 and potentially automatically added to the library when a sufficient number of computers contain the files. Then, periodically or continuously if the user is online via the modem, 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. Novel encryption procedures are also disclosed.

Claims

1. A system for backing up files in user computers, comprising:

a data center including a common library of computer data;

a plurality of user computers remote from the data center and in communication with the data center;

common library logic means for determining which if any of data blocks of the user computers are common computer file blocks by virtue of being contained in the common library, computer file blocks that are determined not to be common computer file blocks being non-common file blocks; and

common library addition means for adding to the common library a non-common file block when the non-common file block appears at least a predetermined number of times in the user computers.

2. The system of claim 1, further comprising:

initialization logic means associated with each user computer for causing file blocks except common file blocks to be transmitted to the data center;

subfile incremental back up logic means associated with each user computer for determining changed blocks that have been changed since a predetermined back up time and generating changed block signals in response thereto;

chunk transmission logic means responsive to the subfile incremental logic means for sending only changed blocks to the data center in chunks having a predetermined size;

synchronizing logic means responsive to the changed block signals for synchronizing the subfile incremental logic means; and

logic means for generating a listing of the blocks of the files stored at the data center and, associated with each block, the first two characters of the block and a digital signature of the block, the subfile incremental logic means using the listing to undertake the determining function.

3. The system of claim 1, wherein a non-common file block is added to the common library when the non-common file block appears in at least a predetermined number of user computers.

4. The system of claim 2, further comprising:

logic means for periodically copying remote versions at the data center onto a portable data storage medium; and

logic means for restoring local files by copying remote versions from the portable data storage medium when the remote versions stored on the portable data storage medium are at least as current as the remote versions stored at the data center, and otherwise restoring local files by copying remote versions from the data center.

5. A computer-implemented method for backing up at least one local computer file from at least one user computer in a computer network, comprising:

(a) transmitting the local file to a data center remote from the user computer to render a remote version, the data center being accessible via the computer network;

(b) receiving changes to at least a first block of the local file, the changes being established by a user of the user computer generating input events;

(c) immediately upon receiving the changes, designating at least the first block as a transmission block to be transmitted to the data center for updating the remote version;

(d) transmitting at least the first block to the data center substantially while the user is generating input events;

(e) for each of the blocks in the local file copying two respective characters thereof defining respective first comparison values and generating respective digital signature codes defining second comparison values;

(f) for each block, periodically determining a test digital signature code and comparing it to the respective second comparison value; and

(g) when the test digital signature code of a block does not equal the respective second comparison value, determining whether the first two characters of the block equal one of the first comparison values.

6. The computer-implemented method of claim 5, wherein the transmitting step is undertaken between input events.

7. The computer-implemented method of claim 5, further comprising the steps of:

(h) when the first two characters equal one of the first comparison values, determining a block digital signature code using a test byte_i as the first byte of a test block;

(i) determining whether the block digital signature code equals one of the second comparison values;

(j) when the block digital signature code equals one of the second comparison values, returning "resynchronized";

otherwise

(k) when either the first two characters of the test byte_i do not equal one of the first comparison values, or when the block digital signature code does not equal one of the second comparison values, setting i=i+1 and repeating select steps.

8. The computer-implemented method of claim 7, further comprising the steps of:

for at least some of the local file blocks, determining whether a duplicate of the local file block is stored in a common file block library at the data center; and

undertaking step (a) only when a duplicate of the local file block is not stored in a common file block library.

9. The computer-implemented method of claim 8, further comprising the steps of:

periodically copying remote versions at the data center onto a portable data storage medium; and

restoring local file blocks by copying remote versions from the portable data storage medium when the remote versions stored on the portable data storage medium are at least as current as the remote versions stored at the data center, and otherwise restoring local file blocks by copying remote versions from the data center.

10. A method for backing up data in a system including user computers and at least one data storage facility, comprising the steps of:

at a user computer, determining whether data associated with the user computer is resident in a common software library associated with the data storage facility;

not backing up the data when the data is resident in the common software library; and

automatically adding the data to the common software library when the data is present in at least a predetermined number of user computers in the system.