SCSI I/O COORDINATOR

• US 20080147893A1
• Filed: 10/31/2006
• Published: 06/19/2008
• Est. Priority Date: 10/31/2006
• Status: Active Grant

• Current Assignee: Valtrus Innovations Limited (f/k/a Dolya Holdco 9 Limited) (Key Patent Innovations Limited)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Krishnamoorthy, Satheesh Kumar Nanniyur, Marripudi, Gunneswara R.
• Granted Patent: US 7,644,204 B2
• Time in Patent Office: Days
• US Class Current: 710/5
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays

Abstract

A Small Computer System Interface (SCSI) input/output (I/O) coordinator of an apparatus in an example caches in memory local to the SCSI I/O coordinator one or more I/O request contexts stored in memory non-local to the SCSI I/O coordinator.

Claims

1. An apparatus, comprising:

a Small Computer System Interface (SCSI) input/output (I/O) coordinator that caches in memory local to the SCSI I/O coordinator one or more I/O request contexts stored in memory non-local to the SCSI I/O coordinator.

2. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator identifies one or more patterns of spatial locality in the plurality of I/O requests.

3. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator groups one or more sets of I/O requests from the plurality of I/O requests based on spatial locality.

4. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator groups one or more sets of I/O requests from the plurality of I/O requests based on one or more of device latency and/or command latency associated with the one or more sets of I/O requests.

5. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator creates a plurality of sets of I/O requests from the plurality of I/O requests as heterogeneous I/O traffic based on a first category of high storage device latency and high I/O command latency, a second category of high storage device latency and low I/O command latency, a third category of low storage device latency and high I/O command latency, and a fourth category of low storage device latency and low I/O command latency.

6. The apparatus of claim 5, wherein the SCSI I/O coordinator prioritizes among the plurality of sets of I/O requests to positively affect performance of I/O traffic in the fourth category of low storage device latency and low I/O command latency.

7. The apparatus of claim 5, wherein the plurality of I/O requests comprise SCSI I/O requests of different characteristics that comprise command type, targeted SCSI device type, SCSI task attributes, device latencies, and command latencies;

wherein the SCSI I/O coordinator receives the SCSI I/O requests and spatial locality criteria as inputs, wherein the SCSI I/O coordinator identifies spatial locality among the SCSI I/O requests subject to the spatial locality criteria, wherein the SCSI I/O coordinator employs the spatial locality to group the SCSI I/O requests into the first category of high storage device latency and high I/O command latency, the second category of high storage device latency and low I/O command latency, the third category of low storage device latency and high I/O command latency, and the fourth category of low storage device latency and low I/O command latency;

wherein the SCSI I/O coordinator employs the spatial locality to reorder and/or prioritize the SCSI I/O requests.

8. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O creates a plurality of sets of I/O requests from the plurality of I/O requests based on categorization by one or more storage access patterns associated with the plurality of sets of I/O requests.

9. The apparatus of claim 8, wherein the one or more storage access patterns associated with the plurality of sets of I/O requests comprise a sequential access pattern from a characteristic of one or more data intensive computer programs and/or a plurality of targets that correspond to the plurality of sets of I/O requests;

wherein the SCSI I/O coordinator creates the plurality of sets of I/O requests from the plurality of I/O requests based on the sequential access pattern from the characteristic of the one or more data intensive computer programs and/or the plurality of targets that correspond to the plurality of sets of I/O requests.

10. The apparatus of claim 9, wherein the one or more data intensive computer programs comprise one or more user-level data intensive computer applications;

wherein the one or more storage access patterns associated with the plurality of sets of I/O requests comprise the sequential access pattern from a characteristic of the one or more user-level data intensive computer applications and the plurality of targets that correspond to the plurality of sets of I/O requests;

wherein the SCSI I/O coordinator creates the plurality of sets of I/O requests from the plurality of I/O requests based on the sequential access pattern from the characteristic of the one or more user-level data intensive computer applications and the plurality of targets that correspond to the plurality of sets of I/O requests.

11. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective S/O requests, wherein the SCSI I/O coordinator makes a determination that one or more I/O requests among the plurality of I/O requests deserve higher priority as higher-priority S/O requests, wherein the SCSI I/O coordinator changes an ordering of attention to a number of pending I/O requests of the plurality of I/O requests to give the higher priority to the higher-priority I/O requests.

12. The apparatus of claim 1, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator controls a quality of service (QoS) through placement of one or more higher-priority I/O requests of the plurality of I/O requests ahead of one or more lower-priority and already-pending I/O requests of the plurality of I/O requests.

13. An apparatus, comprising:

a Small Computer System Interface (SCSI) input/output (I/O) coordinator that purges from memory local to the SCSI I/O coordinator one or more I/O request contexts stored in memory non-local to the SCSI I/O coordinator to make room in the memory local to the SCSI I/O coordinator for one or more additional I/O request contexts more-recently stored in the memory non-local to the SCSI I/O coordinator.

14. The apparatus of claim 13, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O identifies one or more I/O requests of the plurality of I/O requests through employment of one or more respective initiator/target/logical unit/queue (ITLQ) nexuses.

15. The apparatus of claim 13, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O identifies the plurality of I/O requests through employment of a respective plurality of initiator/target/logical unit/queue (ITLQ) nexuses;

wherein the SCSI I/O coordinator identifies spatial locality within a particular ITLQ nexus of the plurality of ITLQ nexuses and across different ITLQ nexuses of the plurality of ITLQ nexuses.

16. The apparatus of claim 13, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O identifies one or more I/O requests of the plurality of I/O requests with one or more respective nexuses that comprise corresponding indications of a block address for target data of each I/O request of the one or more I/O requests, storage device type for the target data of each I/O request of the one or more I/O requests, and SCSI command attributes for each I/O request of the one or more I/O requests.

17. An apparatus, comprising:

a Small Computer System Interface (SCSI) input/output (I/O) coordinator that applies spatial locality criteria to improve cache hit rate in memory local to the SCSI I/O coordinator for of one or more I/O request contexts stored in memory non-local to the SCSI I/O coordinator.

18. The apparatus of claim 17, wherein upon a cache miss for one or more of the of one or more I/O request contexts in the memory local to the SCSI I/O coordinator, the SCSI I/O coordinator retrieves the one or more of the of one or more I/O request contexts from the memory non-local to the SCSI I/O coordinator.

19. The apparatus of claim 17, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator identifies spatial locality in one or more of the plurality of I/O requests through employment of one or more of SCSI command type, SCSI device type, SCSI task attribute, and/or SCSI transport factor.

20. The apparatus of claim 17, wherein a plurality of I/O request contexts comprises the one or more I/O request contexts, wherein the SCSI I/O coordinator associates the plurality of I/O request contexts with a plurality of respective I/O requests, wherein the SCSI I/O coordinator employs as the spatial locality criteria one or more of a specific ITLQ nexus that allows the SCSI I/O coordinator to identify spatial locality for any particular ITLQ nexus, a set of ITLQ nexuses that allows the SCSI I/O coordinator to identify spatial locality on a per-ITLQ nexus for a plurality of ITLQ nexuses, SCSI command operational code that allows the SCSI I/O coordinator to identify spatial locality among I/O requests of the plurality of I/O requests that comprise the command operational code, SCSI device type that allows the SCSI I/O coordinator to identify spatial locality among I/O requests of the plurality of I/O requests that are targeted to the SCSI Device type, SCSI I/O timer rules that allow the SCSI I/O coordinator to identify spatial locality among I/O requests of the plurality of I/O requests, and/or spatial locality interval that allows the SCSI I/O coordinator to identify spatial locality for I/O requests of the plurality of I/O requests that are expected to complete within the spatial locality interval across different ITLQ nexuses.