Data transmission from raid devices

• US 20030016596A1
• Filed: 07/17/2001
• Published: 01/23/2003
• Est. Priority Date: 07/17/2001
• Status: Active Grant

• Current Assignee: SeaChange International Incorporated
• Original Assignee: SeaChange International Incorporated
• Inventors: Trasatti, Philip J., Raspuzzi, Michael D., Mann, Bruce, Chiquoine, Kenneth F.
• Granted Patent: US 6,950,966 B2
• Time in Patent Office: Days
• US Class Current: 369/34.01
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/1088 Reconstruction on already foreseen single or plurality of spare disks
• CPC Class Codes: G06F 2211/1028 Distributed, i.e. distributed RAID systems with parity

Abstract

A redundant array includes a plurality of disks, a bus coupling the disks, a receiving device, and a device to reconstruct a block stored in one of the disks. The device reconstructs the block with associated data and parity blocks from other disks. The device transmits the reconstructed block to the receiving device in response to the one of the disks being unavailable or degraded.

Claims

1. A method for reading data from a clustered system of a plurality of redundant array of inexpensive disks (RAID) device configurations, the method comprises:

receiving a message from a requesting one of members of the clustered system that indicates a next location for a particular block for a subsequent read operation from a drive in the RAID device; and

returning to the requesting one of members of the clustered system a hint that indicates the state of the drive in the RAID device corresponding to location for the subsequent read operation.

2. The method of claim 1 wherein the hint indicates that performance of the device is degraded or the device is unavailable.

3. The method of claim 1 wherein the system returns a next bad byte offset message to the requesting device.

4. The method of claim 1 wherein the requesting member will skip the drive and instead read redundant information and at least one data block one of the other drives in the RAID device.

5. The method of claim 1 wherein the requesting member will reconstruct data from the skipped drive from read redundant information from one of the other drives in the RAID device.

6. The method of claim 1 further comprising:

performing an XOR operation on parity and data to reconstruct the missing data corresponding to data on the skipped drive.

7. The method of claim 1 further comprising:

requesting a first disk of the RAID configuration to transmit a first data block stored therein to a receiving device;

reconstructing the first data block from associated data stored in other disks of the RAID configuration; and

transmitting the reconstructed first data block directly to the receiving device.

8. The method of claim 7 wherein the reconstructing and the transmitting are performed in response to receiving the hint indicating that performance of the device is degraded or the device is unavailable.

9. The method of claim 6 wherein a disk returns a next bad byte offset, and the requesting system receives the next bad byte offset and determines that the RAID array has a bad or reconstructing drive.

10. The method of claim 1 wherein returning the hint instructs the requesting member to start a recovery process or requesting process without waiting for degradation of performance to occur.

11. A clustered system of a plurality of redundant array of inexpensive disks (RAID) configurations to transmit data blocks to a receiving device, comprising:

a plurality of cluster members coupled so that any one cluster member can deliver data to at least some of remaining cluster members, each cluster member comprising;

a plurality of disks adapted to store the blocks and to transmit the stored blocks to the receiving device;

a processor to control reads from and writes to the plurality of disks; and

a process to receive a message that indicates a next location for a particular block for a subsequent read operation from a drive in the RAID device and produce a hint that indicates the state of the drive in the RAID device corresponding to location for the subsequent read operation.

12. The configuration of claim 11 further comprising:

a device to reconstruct a particular block from associated blocks and to transmit the reconstructed block to a receiving device in response to the hint that indicates the state of the drive in the redundant arrays of inexpensive disks.

13. The configuration of claim 11 wherein the processor starts a recovery process based on a state of the hint.

14. The configuration of claim 11 wherein a disk controller returns a next bad byte offset, and the requesting system receives the next bad byte offset and determines that the RAID array has a bad or reconstructing drive.

16. The configuration of claim 15 further comprising:

a device to reconstruct a particular block from associated blocks and parity information and to transmit the reconstructed block to a receiving device in response to the hint that indicates the state of the drive in the second level redundant arrays of inexpensive disks.

17. The configuration of claim 15 wherein the hint indicates that performance of the device is degraded or the device is unavailable.

15. A clustered configuration comprises:

a plurality of clustered nodes each node comprising a redundant array of inexpensive disks (RAID) and a processor adapted to write blocks to and read blocks from the arrays; and

a process to receive a message that indicates a next location for a particular block for a subsequent read operation from a drive in the redundant arrays of inexpensive disks of one of the nodes and produce a hint that indicates the state of the drive in the redundant arrays of inexpensive disks corresponding to location for the subsequent read operation.