File system filter driver apparatus and method

• US 6,266,785 B1
• Filed: 09/01/1998
• Issued: 07/24/2001
• Est. Priority Date: 09/01/1998
• Status: Expired due to Term

• Current Assignee: Teradata US, Inc. (Teradata Corporation)
• Original Assignee: NCR Corporation (NCR Voyix Corporation)
• Inventors: McDowell, Steven R.
• Primary Examiner(s): LE, DIEU MINH T
• Application Number:
  US09/144,753
• Time in Patent Office: 1,057 Days
• Field of Search: 714/11, 714/12, 714/13, 714/10, 707/10, 707/204, 707/205
• US Class Current: 714/11
• CPC Class Codes: G06F 11/203 using migration
• CPC Class Codes: G06F 11/2035 without idle spare hardware
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: G06F 11/2046 where the redundant components share persistent storage G06F11/2043 takes precedence
• CPC Class Codes: G06F 11/2048 where the redundant components share neither address space nor persistent storage

Abstract

A computing apparatus that is capable of taking over processing from a primary computer. The computing apparatus includes a confirmation-based file system cache flush mechanism that prevents loss of uncommitted data during a primary computer failure and a filter driver that is capable of functioning as a network file system driver in a first mode of operation and as an invisible pass through to the underlying local file system driver in a second mode of operation. A computer system that includes a primary and a secondary computer that have these features is also disclosed.

Claims

1. A computing apparatus, comprising:

processing logic;

a file system cache memory coupled to said processing logic;

a layered driver operating system implemented by said processing logic;

a network adapter mechanism coupled to said processing logic to permit said computing apparatus to communicate with another computing apparatus;

a file system filter driver, included within said layered driver operating system, that is capable of performing a software implemented switch between a first mode in which data storage is achieved using a network file system transfer and a second mode in which data storage is achieved using a local file system transfer;

a mechanism for receiving a successful memory write confirmation signal from another computing apparatus;

failure detecting logic that detects failure in another computing apparatus that owns a network file system through which data from said computing apparatus is stored in said first mode of operation; and

fail-over invoking logic that in response to detection of a failure by said failure detecting logic, causes said filter driver to switch from network file system transfers to local file system transfers; and

wherein in the absence of a successful write confirmation signal received by said receiving mechanism, said failure detecting logic generates a failure signal and in response thereto said fail-over invoking logic writes file system cache memory data for which a confirmation signal was not received to a physical storage media associated with said computing apparatus.

2. The computing apparatus of claim 1, further comprising:

cache flush logic coupled to said processing logic and said memory write confirmation mechanism that is capable of flushing from said file system cache memory data written to a physical storage media owned by another computing apparatus coupled at said network adapter mechanism upon receipt of a successful memory write confirmation signal for the data from that other computer.

3. The computing apparatus of claim 2, further comprising:

a file replication mechanism that replicates data in a physical storage media owned by another computing apparatus to a physical storage media associated with said computing apparatus; and

wherein said cache flush logic does not flush file system cache memory data until a memory write confirmation signal for that data is received from the physical storage media associated with said computing apparatus.

4. The computing apparatus of claim 1, wherein said layered driver operating system includes a file system driver and said file system filter driver is provided between an application layer and said file system driver.

5. A computer system, comprising:

a primary computer including

first processing logic;

a first layered driver operating system implemented by said first processing logic; and

a first network adapter mechanism coupled to said first processing logic to permit said primary computer to communicate with another computer; and

a secondary computer including

second processing logic;

a file system cache memory coupled to said second processing logic;

a second layered driver operating system implemented by said second processing logic; and

a second network adapter mechanism coupled to said second processing logic to permit said second computer to communicate with another computer;

confirmation detection logic, included within said primary computer, coupled to said first processing logic for generating a confirmation signal to be sent to said secondary computer when data from said secondary computer is successfully written to a physical storage media having a file system owned by said primary computer;

a file system filter driver, included within said second layered driver operating system, that performs a software implemented switch, when said confirmation signal is not received from said primary computer, from a first mode of operation in which data storage is achieved with a file system owned by said primary computer to a second mode of operation in which data storage is achieved with a file system owned by said secondary computer;

failure detecting logic that detects failure in said primary computer; and

fail-over invoking logic coupled to said second processing logic that in response to detection of a failure by said failure detecting logic, causes said filter driver to switch from network file system transfers to local file system transfers.

6. The computer system of claim 5, further comprising:

cache flush logic coupled to said second processing logic that flushes from said file system cache memory data written to a physical storage media owned by said primary computer upon receipt of a successful memory write confirmation signal for that data from primary computer.

7. The computer system of claim 6, further comprising:

a file replication mechanism that replicates data in a physical storage media owned by said primary computer to a physical storage media owned by said secondary computer; and

wherein said cache flush logic does not flush file system cache memory data until a memory write confirmation signal for that data is received from the physical storage media owned by said secondary computer.

8. The computer system of claim 5, wherein said second layered driver operating system includes a file system driver and said file system filter driver is provided between an application layer and said file system driver.

9. A computing apparatus, comprising:

processing logic;

a file system cache memory coupled to said processing logic;

a layered driver operating system implemented by said processing logic;

a network adapter mechanism coupled to said processing logic to permit said computing apparatus to communicate with another computing apparatus;

a mechanism coupled to said processing logic that receives a successful memory write confirmation signal from another computer that owns a physical storage media to which data from said computing apparatus is stored in a first mode of operation;

cache flush logic coupled to said processing logic and said memory write confirmation mechanism that flushes from said file system cache memory data written to a physical storage media owned by another computing apparatus coupled at said network adapter mechanism upon receipt of a successful memory write confirmation signal for the data from that other computing apparatus;

a file system filter driver, included within said layered operating system, that is capable of performing a software implemented switch between said first mode of operation in which data storage is achieved using a network file system transfer and a second mode of operation in which data storage is achieved using a local file system transfer; and

wherein the absence of a successful write confirmation signal received by said receiving mechanism causes said filter driver to switch from said first mode of operation to said second mode of operation.

10. The computing apparatus of claim 9, further comprising:

a file replication mechanism that replicates data in a physical storage media owned by another computing apparatus to a physical storage media associated with said computing apparatus; and

wherein said cache flush logic does not flush file system cache memory data until a memory write confirmation signal for that data is received from the physical storage media associated with said computing apparatus.

11. The computing apparatus of claim 9, wherein said layered driver operating system includes a file system driver and said file system filter driver is provided between an application layer and said file system driver.