Serial advanced technology attachment (SATA) switch

• US 20040252716A1
• Filed: 02/09/2004
• Published: 12/16/2004
• Est. Priority Date: 06/11/2003
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Nemazie, Sam
• Granted Patent: US 7,523,235 B2
• Time in Patent Office: Days
• US Class Current: 370/447
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence

Abstract

An embodiment of the present invention is disclosed to include a SATA Switch allowing for access by two hosts to a single port SATA device Further disclosed are embodiments for reducing the delay and complexity of the SATA Switch.

Claims

1. A switch coupled between a plurality of host units and a device for communicating there between and comprising:

a) a first serial advanced technology attachment (ATA) port coupled to a first host unit;

b) a second serial ATA port coupled to a second host unit;

c) a third serial ATA port coupled to a device; and

d) an arbitration and control circuit for selecting one of the first host or second host units to be coupled to the device, through the switch, whenever either one of the first or second host units sends commands for execution thereof by the device.

2. A switch as recited in claim 1 wherein said first serial ATA port includes a first host task file.

3. A switch as recited in claim 1 wherein said second serial ATA port includes a second host task file.

4. A switch as recited in claim 3 wherein said third serial ATA port includes a device task file.

5. A switch as recited in claim 3 wherein said first, second and third ports are level 4 ports.

6. A switch as recited in claim 1 wherein said device is a storage unit.

7. A switch as recited in claim 1 wherein said switch is employed in an enterprise system.

8. A switch as recited in claim 1 wherein said arbitration and control circuit causes concurrent access of the device by the first and second host units.

9. A switch as recited in claim 1 wherein information, in the form of data, commands or setup, is transferred from the device to the first or second host units through the switch and the information is modified by the switch prior to being received by the first or second host units such that modified information rather than the information is received by the first or second host units.

10. A switch as recited in claim 9 wherein the information is referred to as ‘

identify drive response’

.

11. A switch as recited in claim 9 wherein the information is referred to as ‘

Tag’

.

12. A switch as recited in claim 1 wherein information, in the form of data, commands or setup, is transferred from the first or second host units to the device through the switch and the information is modified by the switch prior to being received by the device such that modified information rather than the information is received by the device.

13. A switch as recited in claim 12 wherein the information is referred to as ‘

Tag’

.

14. A switch as recited in claim 12 wherein the arbitration and control circuit include a Tag/Sactive Mapping Circuit for mapping a host tag to a device tag and inverse mapping for identifying a host.

15. A switch as recited in claim 1 wherein either the first or the second host sends a legacy queue command queued by the device.

16. A switch as recited in claim 1 wherein either the first or the second host sends a native queue command for for execution thereof by the device.

17. A switch as recited in claim 16 where the Tag in the native queue command is modified prior to sending to the Device to avoid using the same Tag for both hosts and not to exceed the maximum allowed Tag value.

18. A switch as recited in claim 17 where the Tag received in a FIS from Device is modified to its original value prior to sending to the Host.

19. A switch as recited in claim 1 wherein the first, second and third ports are level 3 serial ATA ports and a Data FIS FIFO and an associated FIFO Control are coupled to the first, second and third ports and are located externally thereto.

20. A switch comprising:

a) a first serial advanced technology attachment (ATA) port for connection to a first host unit;

b) a second serial ATA port for connection to a second host unit;

c) a third serial ATA port for connection to a device; and

d) an arbitration and control circuit for selecting either the first host unit or the second host unit to be coupled to the device, through the switch, when either host units sends commands for execution by the device,

wherein while one of the first or second host units is coupled to the device, through the switch, the other one of the first or second host units sends a command to the switch for execution by the device.

21. A switch as recited in claim 20 wherein the switch is a serial ATA switch.

22. A switch as recited in claim 20 wherein said first serial ATA port includes a first host task file.

23. A switch as recited in claim 22 wherein said second serial ATA port includes a second host task file.

24. A switch as recited in claim 23 wherein said third serial ATA port includes a device task file.

25. A switch as recited in claim 20 wherein said device is a storage unit.

26. A switch as recited in claim 20 wherein said switch is employed in an enterprise system.

27. A switch as recited in claim 20 wherein said arbitration and control causes concurrent access of the device by the first and second host units.

28. A switch as recited in claim 20 wherein information, in the form of data, commands or setup, is transferred from the device to the first or second host units through the switch and the information is modified by the switch prior to being received by the first or second host units such that modified information rather than the information is received by the first or second host units.

29. A switch as recited in claim 28 wherein the information is referred to as “

TAG”

.

30. A switch as recited in claim 28 wherein the information is referred to as ‘

identity drive response’

.

31. A switch as recited in claim 20 wherein information, in the form of data, commands or setup, is transferred from the first or second host units to the device through the switch and the information is modified by the switch prior to being received by the device such that modified information rather than the information is received by the device.

32. A switch as recited in claim 31 wherein the information is referred to as ‘

Tag’

.