STORAGE SYSTEM INCLUDING A PLURALITY OF NETWORKED STORAGE NODES

• US 20180067649A1
• Filed: 02/21/2017
• Published: 03/08/2018
• Est. Priority Date: 09/05/2016
• Status: Active Grant

• Current Assignee: Kioxia Corporation
• Original Assignee: Toshiba Memory Corporation (Kioxia Corporation)
• Inventors: SHIMAMURA, Makoto, KANEMATSU, Mototaka
• Granted Patent: US 10,514,849 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays

Abstract

A storage system includes a plurality of nodes, each of the nodes including a processor and a nonvolatile storage device, and a connection unit directly connected to at least one of the nodes and configured to issue commands directed to a target node. The processor of the target node is configured to access the nonvolatile storage device of the target node in accordance with a command received from the connection unit, notify completion of processing for the command to the connection unit when a processing result responsive to the command is returned from the nonvolatile storage device of the target node within a reference time period, and notify a busy state of the target node to the connection unit when the processing result responsive to the command is not returned from the nonvolatile storage device of the target node within the reference time period.

Claims

1. A storage system comprising:

a plurality of nodes, each of the nodes including a processor and a nonvolatile storage device; and

a connection unit directly connected to at least one of the nodes and configured to issue commands to a target node, wherein

the processor of the target node is configured to

access the nonvolatile storage device of the target node in accordance with a command received from the connection unit,

notify completion of processing for the command to the connection unit when a processing result responsive to the command is returned from the nonvolatile storage device of the target node within a reference time period, and

notify a busy state of the target node to the connection unit when the processing result responsive to the command is not returned from the nonvolatile storage device of the target node within the reference time period.

2. The storage system according to claim 1, wherein

the connection unit is further configured to hold, in a memory thereof, one or more commands directed to the target node without issuing the commands to the target node, when the target node is in the busy state.

3. The storage system according to claim 2, wherein

the processor of the target node is further configured to notify the completion of the processing and a non-busy state of the target node to the connection unit when the processing result is returned from the nonvolatile storage device of the target node after the reference time period has passed.

4. The storage system according to claim 3, wherein

the connection unit is further configured to issue the commands held in the memory to the target node, responsive to being notified by the target node of the non-busy state thereof.

5. The storage system according to claim 1, wherein

the processor of the target node is further configured to maintain an average value of time periods taken for the nonvolatile storage device of the target node to complete processing for each type of commands, and calculate the reference time period for the command received from the connection unit based on the average value corresponding to its type.

6. The storage system according to claim 5, wherein

the processor of the target node is further configured to maintain a standard deviation of the time periods taken for the nonvolatile storage device of the target node to complete processing for each type of commands, and calculate the reference time period for the command received from the connection unit also based on the standard deviation corresponding to its type.

7. The storage system according to claim 1, wherein

the processor of the target node returns a completion notification to the connection unit to notify the completion of processing for the command, and returns a busy notification to the connection unit to notify the busy state of the target node.

8. The storage system according to claim 7, wherein

the target node includes a plurality of ports, and the completion notification and the busy notification are output through different ports.

9. The storage system according to claim 1, wherein

the processor of the target node stores data indicating a completion state or data indicating the busy state in a register thereof that is accessible from the connection unit.

10. The storage system according to claim 1, wherein

the nonvolatile storage device of the target node does not accept commands from the processor of the target node if a garbage collection process is being carried out until the completion of the garbage collection process.

11. A method of carrying out data access in a storage system including a plurality of nodes, each of which includes a nonvolatile storage device, and a connection unit directly connected to at least one of the nodes, comprising:

accessing a nonvolatile storage device of a target node in accordance with a command received from the connection unit;

notifying completion of processing for the command to the connection unit when a processing result responsive to the command is returned from the nonvolatile storage device of the target node within a reference time period; and

notifying a busy state of the target node to the connection unit when the processing result responsive to the command is not returned from the nonvolatile storage device of the target node within the reference time period.

12. The method according to claim 11, further comprising:

holding, in a memory of the connection unit, one or more commands directed to the target node without issuing the access commands to the target node, when the target node is in the busy state.

13. The method according to claim 12, further comprising:

notifying the completion of the processing and a non-busy state of the target node to the connection unit when the processing result is returned from the nonvolatile storage device of the target node after the reference time period has passed.

14. The method according to claim 13, further comprising:

issuing the commands held in the memory to the target node, responsive to being notified of the non-busy state of the target node.

15. The method according to claim 11, further comprising:

maintaining, in the target node, an average value of time periods taken for the nonvolatile storage device of the target node to complete processing for each type of commands; and

calculating the reference time period for the command received from the connection unit based on the average value corresponding to its type.

16. The method according to claim 15, further comprising:

maintaining, in the target node, a standard deviation of the time periods taken for the nonvolatile storage device of the target node to complete processing for each type of commands, wherein

the reference time period for the command received from the connection unit is calculated also based on the standard deviation corresponding to its type.

17. The method according to claim 11, wherein

notifying the completion of processing for the command includes returning a completion notification to the connection unit, and

notifying the busy state of the target node includes returning a busy notification to the connection unit.

18. The method according to claim 17, wherein

the target node includes a plurality of ports, and the completion notification and the busy notification are output through different ports.

19. The method according to claim 11, wherein

notifying the completion of processing for the access command includes storing data indicating a completion state in a register of the target node that is accessible from the connection unit, and

notifying the busy state of the target node includes storing data indicating the busy state in the register.

20. The method according to claim 11, wherein

the nonvolatile storage device of the target node does not accept commands if a garbage collection process is being carried out until the nonvolatile storage device completes the garbage collection process.