Read-after-write verification for improved write-once-read-many data storage

• US 7,558,839 B1
• Filed: 09/14/2005
• Issued: 07/07/2009
• Est. Priority Date: 12/14/2004
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: McGovern, William P.
• Primary Examiner(s): Hwang; Joon H
• Assistant Examiner(s): Myers; Jasmine
• Application Number:
  US11/227,812
• Time in Patent Office: 1,392 Days
• Field of Search: 709/218, 709/217, 707/200, 360/53
• US Class Current: 709/218
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0637 Permissions
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G11B 20/1879 Direct read-after-write methods
• CPC Class Codes: G11B 2220/2516 Hard disks

Abstract

A user interface in a file-based networked storage server enables a user to selectively enable or disable an option to require read-after-write verification for sets of data stored by the file-based networked storage server. In response to a request from a client, specified data is written to a magnetic storage device managed by the file-based networked storage server. A determination is made of whether the specified data is associated with a set of data for which the option to require read-after-write verification is enabled, and if so, then the specified data written to the magnetic storage device is verified, prior to, and as a precondition of, acknowledging completion of the write to the client. The specified data written to the magnetic storage device is designated as being in a WORM state only after successful completion of said writing and said verifying.

Claims

1. A method comprising:

providing a user interface, in a file-based networked storage server, to enable a user to selectively enable or disable an option to require read-after-write verification individually for each of a plurality of sets of data stored by the file-based networked storage server;

receiving from a client a request to perform a write of specified data;

writing the specified data to a magnetic storage device managed by the file-based networked storage server in response to the request;

determining whether the specified data is associated with a set of data, of said plurality of sets of data, for which said option to require read-after-write verification is enabled;

if the specified data is associated with a set of data, of said plurality of sets of data, for which said option to require read-after-write verification is enabled, then verifying the specified data written to the magnetic storage device, prior to, and as a precondition of, acknowledging completion of the write of the specified data to the client; and

designating the specified data written to the magnetic storage device as being in a WORM state only after successful completion of said writing and said verifying.

2. A method as recited in claim 1, wherein said verifying comprises:

reading back the specified data from the magnetic storage device into the file-based networked storage server; and

in the file-based networked storage server, comparing the specified data read back with the data written to verify that the data read back is identical to the specified data written.

3. A method as recited in claim 1, further comprising sending a write-and-verify command to the magnetic storage device, wherein the magnetic storage device performs said verifying.

4. A method as recited in claim 1, further comprising performing read-after-write verification of a directory structure with which the specified data is associated.

5. A method as recited in claim 1, wherein the file-based network storage server;

provides the client with file-level access to stored data.

6. A method as recited in claim 1, further comprising checking context of the specified data written to determine whether to perform the verification.

7. A method as recited in claim 1, wherein said providing a user interface comprises allowing users to select any of a plurality of volumes for which to enable read-after-write verification.

8. A method as recited in claim 7, wherein said determining comprises determining whether the specified data is part of a volume for which said option to require read-after-write verification is enabled.

9. A method as recited in claim 1, wherein each of the sets of data, of said plurality of sets of data, is a volume of data.

10. A storage server comprising:

a processor;

a network adapter through which to communicate with a client;

a storage adapter through which to access a plurality of magnetic storage devices;

a file system to manage a plurality of stored files stored in the plurality of magnetic storage devices;

a user interface to enable a user to selectively enable or disable an option to require read-after-write verification individually for each of a plurality of sets of data stored by the storage server in the plurality of magnetic storage devices; and

memory storing software which, when executed by the processor, causes the storage server to execute a read-after-write verification process that includes;

receiving from the client a request to perform a write of specified data;

writing the specified data to a magnetic storage device of the plurality of magnetic storage devices in response to the request;

determining whether the specified data is associated with a set of data, of said plurality of sets of data, for which said option to require read-after-write verification is enabled;

if the specified data is associated with a set of data, of said plurality of sets of data, for which said option to require read-after-write verification is enabled, then causing the specified data written to the magnetic storage device to be verified, prior to, and as a precondition of, acknowledging completion of the write to the client; and

designating the specified data written to the magnetic storage device as being in a WORM state only after successful completion of said writing and said verifying.

11. A storage server as recited in claim 10, wherein said causing the specified data written to the magnetic storage device to be verified comprises:

reading back the specified data from the magnetic storage device into the storage server; and

in the storage server, comparing the data read back with the specified data written to verify that the specified data read back is identical to the data written.

12. A storage server as recited in claim 10, wherein the read-after-write verification process further comprises sending a write-and-verify command to the magnetic storage device, wherein the magnetic storage device verifies the specified data.

13. A storage server as recited in claim 10, wherein the read-after-write verification process further comprises causing read-after-write verification of a directory structure with which the specified data is associated to be performed.

14. A storage server as recited in claim 10, wherein the storage server provides the client with file-level access to stored data.

15. A storage server as recited in claim 10, wherein the read-after-write verification process further comprises checking context of the specified data written to determine whether to perform the verification.

16. A storage server as recited in claim 10, wherein said providing a user interface comprises allowing users to select any of a plurality of volumes for which to enable read-after-write.

17. A storage server as recited in claim 16, wherein said determining comprises determining whether the specified data is part of a volume for which said option to require read-after-write verification is enabled.

18. A storage server as recited in claim 10, wherein each of the sets of data, of said plurality of sets of data, is a volume of data.

19. An apparatus comprising:

a processor;

means for selectively specifying individually whether read-after-write verification is to be performed for each of a plurality of sets of data stored by a file-based networked storage server;

means for receiving from a client a request to perform a write of specified data;

means for writing the specified data to a magnetic storage device managed by the file-based networked storage server in response to the request;

means for determining whether the specified data is to be subject to read-after-write verification;

means for verifying the specified data written to the magnetic storage device if the specified data is to be subject to read-after-write verification, prior to, and as a precondition of, acknowledging completion of the write to the client; and

means for designating the specified data written to the magnetic storage device as being in a WORM state only after successful completion of said writing and said verifying.

20. An apparatus as recited in claim 19, where the means for determining whether the specified data is to be subject to read-after-write verification comprises means for determining whether a read-after-write verification option is enabled for the specified data.

21. A method comprising:

providing a user interface, in a file-based networked storage server, to enable a user to selectively enable or disable an option to require read-after-write verification individually for each of a plurality of volumes of data stored by the file-based networked storage server;

receiving from a client a request to perform a write of specified data;

mapping the request to a corresponding volume of the plurality of volumes;

writing the specified data to said volume in a magnetic storage device managed by the file-based networked storage server in response to the request, and thereafter, determining whether said option to require read-after-write verification is enabled for said volume;

if said option to require read-after-write verification is determined to be enabled for said volume, then verifying the specified data written to the magnetic storage device, prior to, and as a precondition of, acknowledging completion of the write to the client; and

designating the specified data written to the magnetic storage device as being in a WORM state only after successful completion of said writing and said verifying.