Process and article of manufacture for constructing and optimizing transaction logs for mobile file systems

• US 5,745,750 A
• Filed: 12/15/1995
• Issued: 04/28/1998
• Est. Priority Date: 12/15/1995
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Porcaro, Thomas Joseph
• Primary Examiner(s): Black, Thomas G.
• Assistant Examiner(s): Coby, Frantz
• Application Number:
  US08/572,923
• Time in Patent Office: 865 Days
• Field of Search: 395/613, 395/602, 395/612, 395/650, 395/575, 364/200
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1438 Restarting or rejuvenating
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface

Abstract

A process and article of manufacture for optimally logging and replaying file system transactions from a mobile file system. The process logs file system transactions in chronological order except for file and directory object renaming transactions that are logged before all other transactions. Each transaction log entry includes a transaction type and file identifier that is expanded dynamically during the replay cycle. The dynamic expansion of the identifier reduces the number of log entries required where file or directory objects are renamed. The transaction log is optimized as each transaction is inserted or appended on the client. The optimization process eliminates transactions that are rendered invalid or superfluous by the most recent transaction. The dynamic expansion feature allows RENAME transactions to be optimized because MKDIR and CREATE transactions automatically are expanded to the new file system object name, eliminating the need to log the RENAME transaction. Successive RENAME transactions are folded into a single RENAME transaction to reduce log size and playback resource requirements.

Claims

1. A method for optimizing a file system transaction log for a computer file system, the computer system having a processor means and memory means, the method comprising the steps of:

capturing file system transactions;

testing each of said file system transaction for transaction type;

inserting each object rename transaction as a rename transaction log entry having a dynamic path identifier into a transaction log following other object rename transactions and before all other transactions;

appending all other non-rename object transactions as a file system transaction log entry having a dynamic path identifier at the end of said transaction log.

2. The method of claim 1, in which said object rename transactions include file rename transactions and directory rename transactions.

3. The method of claim 1 wherein said non-rename object transactions include file and directory operation transactions.

4. The method of claim 1, further comprising the steps of:

optimizing said transaction log by eliminating superseded transactions.

5. The method of claim 4 wherein the optimizing step for rename transactions includes the steps of:

scanning said transaction log for a mkdir transaction that matches the rename transaction and performing the inserting each object rename transaction step only if no mkdir transaction is found;

scanning said transaction log for a create transaction that matches the rename transaction and performing the inserting each object rename transaction step only if no create transaction is found;

scanning said transaction log for a rename transaction that matches the rename transaction and, if found, changing the "new" object name in the found rename transaction and propagating the "new" name to other object rename transactions, and inserting each new object rename transaction only if no rename transaction is found.

6. The method of claim 1, wherein said rename transaction log entry includes a transaction type, a file identifier, an old object name and a new object name.

7. The method of claim 1, wherein the file system transaction log entry dynamic path identifier is a file identifier.

8. A computer program product having a computer readable medium having computer program logic recorded thereon for optimizing a file system transaction log for a computer file system, the computer system having a processor means and memory means, said computer program product comprising:

computer program product means for causing a computer system to capture file system transactions;

computer program product means for causing a computer system to test each of said file system transactions for transaction type;

computer program product means for causing a computer system to insert each object rename transaction as a rename transaction log having a dynamic path identifier into a transaction log following other object rename transactions and before all other non-rename transactions;

computer program product means for causing a computer system to append all other non-rename transactions as a file system transaction log entry having a dynamic path identifier at the end of said transaction log.

9. The program product of claim 8, in which said object rename transactions include file rename transactions and directory rename transactions.

10. The program product of claim 8 wherein said non-rename object transactions include file and directory operation transactions.

11. The program product of claim 8, further comprising:

computer program product means for causing a computer system to optimize said transaction log by eliminating superseded transactions.

12. The program product of claim 11 wherein the computer program means to optimize for rename transactions includes:

computer program product means for causing a computer system to scan said transaction log for a mkdir transaction that matches the rename transaction and performing the inserting each object rename transaction step only if no mkdir transaction is found;

computer program product means for causing a computer system to scan said transaction log for a create transaction that matches the rename transaction and performing the inserting each object rename transaction step only if no create transaction is found;

computer program product means for causing a computer system to scan said transaction log for a rename transaction that matches the rename transaction and, if found, changing the "new" object name in the found rename transaction and propagating the "new" name to other rename object transactions, and inserting each new object rename transaction only if no rename transaction is found.