Method and apparatus for isolating storage devices to facilitate reliable communication

• US 20130080829A1
• Filed: 09/23/2011
• Published: 03/28/2013
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Dot Hill Systems Corporation (Seagate Technology Holdings Plc)
• Original Assignee: Dot Hill Systems Corporation (Seagate Technology Holdings Plc)
• Inventors: Colline, Phillip Raymond
• Granted Patent: US 8,812,913 B2
• Time in Patent Office: Days
• US Class Current: 714/6.22
• CPC Class Codes: G06F 11/0727 in a storage system, e.g. in a DASD or network based storage system drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40

Abstract

A method for maintaining reliable communication on a link between an expander and a storage device is provided. The method includes detecting, by a processor coupled to the link, an error corresponding to the link, and maintaining a count of detected errors for the link, by the processor. The method also includes determining, by the processor, if the count of detected errors is above a first error threshold. If the count of detected errors is not above the first error threshold, then the method repeats the detecting, maintaining, and determining steps. If the count of detected errors is above the first error threshold, then the method provides the processor placing the storage device into a segregated zone.

Claims

1. A method for maintaining reliable communication on a link between an expander and a storage device, comprising:

detecting, by a processor coupled to the link, an error corresponding to the link;

maintaining, by the processor, a count of detected errors for the link; and

determining, by the processor, if the count of detected errors is above a first error threshold;

if the count of detected errors is not above the first error threshold, then repeating detecting, maintaining, and determining; and

if the count of detected errors is above the first error threshold, then placing, by the processor, the storage device into a segregated zone.

2. The method of claim 1, wherein placing the storage device into the segregated zone comprises:

suspending data reads and writes to the storage device;

preventing participation by the storage device in device discovery processes; and

testing, by the processor, the link, wherein testing the link comprises at least one of;

monitoring the link for a predetermined time period;

downshifting the link to a next lower transmission speed, if a lower transmission speed is available;

performing at least one of read buffer commands and write buffer commands to the storage device; and

detecting CRC errors on the link while monitoring the link and performing at least one of read buffer commands and write buffer commands to the storage device.

3. The method of claim 2, wherein if the processor determines the CRC errors are above a second threshold, the processor repeats performing, detecting and calculating, wherein if the CRC errors are not above the second threshold, integrating the link, by the processor.

4. The method of claim 3, wherein integrating the link comprises returning the link to regular operation, wherein regular operation comprises allowing data reads and writes to the storage device and allowing the storage device to participate in device discovery processes.

5. The method of claim 4, wherein at least one of a controller and an administrative computer updates at least one of the first and second thresholds, wherein the controller and administrative computer are coupled to the processor.

6. The method of claim 1, wherein after placing the storage device into the segregated zone the method further comprising:

notifying, by the processor, a controller coupled to the processor that the link is above the first error threshold.

7. The method of claim 6, wherein after notifying the controller that the link is above the first error threshold, the method further comprising:

transferring, by the controller, an indication to an administrative computer coupled to the controller that the storage device is in the segregated zone; and

displaying, by the administrative computer, the storage device in the segregated zone to a user.

8. The method of claim 7, wherein after displaying the storage device in the segregated zone to the user, the method further comprising:

receiving, by the administrative computer, a user indication to override segregating the storage device;

generating, by the administrative computer, a command to the controller to override segregating the storage device;

transferring a message by the controller to the processor to override segregating the storage device; and

removing, by the processor, the storage device from the segregated zone.

9. A system for maintaining reliable communication on a link between an expander and a storage device, comprising:

a processor;

a storage device; and

a link, coupled to the processor and the storage device,

wherein the processor detects an error corresponding to the link, maintains a count of detected errors for the link, and determines if the count of detected errors is above a first error threshold, wherein if the count of detected errors is not above the first error threshold, the processor repeats detects, maintains, and determines, wherein if the count of detected errors is above the first error threshold, then the processor places the storage device into a segregated zone.

10. The system of claim 9, wherein the processor places the storage device into the segregated zone comprises the processor suspends data reads and writes to the storage device, the processor prevents participation by the storage device in device discovery processes, and the processor tests the link, wherein the processor tests the link comprises at least one of the processor monitors the link for a predetermined time period, the processor downshifts the link to a next lower transmission speed, if a lower transmission speed is available, the processor performs at least one of read buffer commands and write buffer commands to the storage device, and the processor detects CRC errors on the link while the processor monitors the link and performs at least one of read buffer commands and write buffer commands.

11. The system of claim 10, wherein if the processor determines the CRC errors are above a second threshold, the processor continues to test the link, wherein if the CRC errors are not above the second threshold, the processor integrates the link.

12. The system of claim 11, wherein the processor integrates the link comprises the processor returns the link to regular operation, wherein regular operation comprises the processor resumes data reads and writes to the storage device.

13. The system of claim 9, wherein the count of detected errors comprises at least one or more of an error count from the storage device, an error count from the expander, and CRC errors corresponding to the link.

14. The system of claim 9, wherein after the processor places the storage device into the segregated zone, the processor notifies a controller coupled to the processor that the link is above the first error threshold.

15. The system of claim 14, wherein after the processor notifies the controller, the controller transfers an indication to an administrative computer coupled to the controller that the storage device is in the segregated zone and the administrative computer displays the storage device in the segregated zone to a user.

16. The system of claim 15, wherein after the administrative computer displays the storage device in the segregated zone to the user, the administrative computer receives a user indication to override segregating the storage device;

in response to the administrative computer user receives the user indication to override segregating the storage device, the administrative computer generates a command to the controller to override segregating the storage device, the controller transfers a message o the processor to override segregating the storage device, and the processor removes the storage device from the segregated zone.

17. A method for maintaining reliable communication on a link between an expander and a storage device, comprising:

detecting, by a processor coupled to the link, an error corresponding to the link;

providing, by the processor, an indication of the error corresponding to the link to a controller coupled to the processor;

maintaining, by the controller, a count of detected errors for the link; and

determining, by the controller, if the count of detected errors is above a first error threshold;

if the count of detected errors is not above the first error threshold, then repeating detecting, providing, maintaining, and determining; and

if the count of detected errors is above the first error threshold, then;

transferring, by the controller, a command to the processor to place the storage device into a segregated zone; and

placing, by the processor, the storage device into the segregated zone.

18. The method of claim 17, wherein placing the storage device into the segregated zone comprises:

suspending data reads and writes to the storage device;

allowing metadata reads by the controller in order to determine if the storage device is part of a RAID volume;

foregoing participation by the storage device in device discovery processes; and

testing, by the processor, the link, wherein testing the link comprises the controller directing the processor to perform at least one of;

monitoring the link for a predetermined time period;

performing at least one of read buffer commands and write buffer commands to the storage device; and

detecting CRC errors on the link while monitoring the link and performing at least one of read buffer commands and write buffer commands to the storage device.

19. The method of claim 18, wherein in response to testing the link, the method further comprising:

generating, by the processor, test results to the controller; and

ascertaining, by the controller, if the test results indicate errors are above a second threshold;

if the errors are above the second threshold;

commanding, by the controller, the processor to repeat monitoring, performing, and detecting; and

if the errors are not above the second threshold;

commanding, by the controller, the processor to integrate the link; and

integrating the link, by the processor.

20. The method of claim 19, wherein integrating the link comprises returning the link to regular operation, wherein regular operation comprises resuming data reads and writes to the storage device.