Storage system with LUN virtualization

• US 20040139240A1
• Filed: 01/15/2003
• Published: 07/15/2004
• Est. Priority Date: 01/15/2003
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: DiCorpo, Jeffrey, Feather, Stanley Smith Jr.
• Granted Patent: US 6,816,917 B2
• Time in Patent Office: Days
• US Class Current: 710/3
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0683 Plurality of storage devices

Abstract

An apparatus comprises a data path capable of coupling a physical device to a plurality of initiators. An interface is coupled to the data path and forms a command pathway between the plurality of initiators and the physical device. The controller is coupled to the data path and coupled to the interface. A controller comprises an executable process that creates a virtual device object that resolves conflicting concurrent attempts to access the physical device by a plurality of initiators. The virtual device object is capable of protecting state of the physical device during successive data transfer and media movement operations by emulating responses of the physical device and redirecting access to the physical device when the physical device becomes available.

Claims

1. An apparatus comprising:

a data path capable of coupling a physical device to a plurality of initiators;

an interface coupled to the data path and forming a command pathway between the plurality of initiators and the physical device;

a controller coupled to the data path and coupled to the interface, the controller comprising an executable process that creates a virtual device object that resolves conflicting concurrent attempts to access the physical device by a plurality of initiators, the virtual device object being capable of protecting state of the physical device during successive data transfer and media movement operations by emulating responses of the physical device and redirecting access to the physical device when the physical device becomes available.

2. The apparatus according to claim 1 wherein:

initiator requests are selectively directed to the physical device and the virtual device object dynamically based on state of the physical device.

3. The apparatus according to claim 1 wherein:

initiator requests are selectively directed to the physical device and the virtual device object based on requests from the plurality of initiators to the physical device and based on physical device status.

4. The apparatus according to claim 1 wherein:

initiator requests are selectively directed to the physical device and the virtual device object based on autonomous requests from the controller.

5. The apparatus according to claim 1 wherein:

the controller can concurrently create a plurality of virtual device objects.

6. The apparatus according to claim 1 wherein:

the virtual device object is configured in the image of the physical device.

7. The apparatus according to claim 1 wherein:

the virtual device object has access to a large storage to simulate data access.

8. The apparatus according to claim 1 wherein:

the virtual device object has a specified general interface definition that enables emulation of a plurality of different physical devices in response to a general set of access requests.

9. The apparatus according to claim 1 wherein:

the virtual device object emulates task management and aspects of control operation.

10. A system capable of managing access to a physical device from among a plurality of initiators, the system comprising:

a virtual device capable of emulating at least one behavior of the physical device;

a command filter capable of communicating with the plurality of initiators and selectively directing initiator requests to the physical device and the virtual device based on physical device state; and

a monitor coupled to the command filter and the physical device and capable of determining state of the physical device and communicating a physical device state signal to the command filter.

11. The system according to claim 10 further comprising:

a process executable in the monitor that analyzes multiple conditions in a background process that extracts a device state parameter from the multiple conditions, the device state parameter for directing filtering of the command filter.

12. The system according to claim 10 further comprising:

an interface coupled to the command filter and coupled to a data path between the initiators, the physical device, and the virtual device, the interface capable of performing a virtual/physical mapping that enables virtualization of the physical device.

13. A system capable of managing traffic on a data path between a physical device and a plurality of initiators, the system comprising:

a virtual device capable of emulating at least one behavior of the physical device;

a command filter capable of alternatively directing commands to the virtual device and the physical device based on a physical device state parameter; and

a monitor coupled to the data path and capable of analyzing multiple conditions in a background process that extracts a physical device state parameter from the multiple conditions, the physical device state parameter for directing filtering of the command filter.

14. The system according to claim 13 further comprising:

a data filter coupled to the monitor and coupled to a data path between the initiators and the physical device, the data filter being capable of accessing data to monitor control information.

15. The system according to claim 13 further comprising:

an interface coupled to the command filter and coupled to a data path between the initiators, the physical device, and the virtual device, the interface capable of performing a virtual/physical mapping that enables virtualization of the physical device.

16. A method of managing access of a plurality of initiators to a physical device comprising:

monitoring requests from the plurality of initiators to the physical device and status of the physical device;

determining whether the physical device is bound to one of the plurality of initiators;

creating a virtual device that emulates at least one action of the physical device; and

directing a request from an unbound initiator to the virtual device if the physical device is bound.

17. The method according to claim 16 further comprising:

detecting that the physical device is busy with a first initiator.

18. The method according to claim 17 further comprising:

sending a request from a second initiator to the virtual device if the physical device is busy with the first initiator or the device state is bound.

19. The method according to claim 16 further comprising:

if the physical device is not busy and the device state is not bound;

sending the command to the physical drive.

20. The method according to claim 16 further comprising:

determining a bound state comprising at least one of detecting media movement to the physical device, intercepting commands to the physical device, intercepting commands to a robotic that transports media to the physical device, detecting a LOAD UNLOAD command to the physical device, detecting a sequence of TEST UNIT READY commands to the physical device, detecting a REWIND command to the physical device, and detecting a specific, unique and repeatable sequence of commands to the physical device.

21. An apparatus for managing access of a plurality of initiators to a physical device comprising:

means for monitoring requests from the plurality of initiators to the physical device and status of the physical device;

means for determining whether the physical device is bound to one of the plurality of initiators;

means for creating a virtual device that emulates at least one action of the physical device; and

means for directing a request from an unbound initiator to the virtual device if the physical device is bound.

22. An apparatus comprising:

a data path capable of coupling a physical device to a plurality of initiators;

an interface coupled to the data path and forming a command pathway between the plurality of initiators and the physical device; and

a controller coupled to the data path and coupled to the interface, the controller comprising an executable process that detects when a data storage device is executing a sequence of data transfer commands in response to an action of a first initiator and intercepts actions from other initiators while the sequence is active.

23. The apparatus according to claim 22 wherein the controller comprises an executable process that detects when a data storage device is executing a sequence of media movement commands in response to an action of the first initiator and intercepts actions from other initiators while the sequence is active.

24. The apparatus according to claim 22 wherein the controller comprises an executable process that detects when a data storage device is executing a sequence of data transfer and media movement commands in response to an action of the first initiator and intercepts actions from other initiators while the sequence is active.