SYSTEM AND METHOD FOR EMULATING SHARED STORAGE

• US 20150033220A1
• Filed: 07/23/2013
• Published: 01/29/2015
• Est. Priority Date: 07/23/2013
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Venkatesan, Vivek, Venkat, Narayan
• Granted Patent: US 9,152,447 B2
• Time in Patent Office: Days
• US Class Current: 718/1
• CPC Class Codes: G06F 2009/4557 Distribution of virtual machine instances; Migration and load balancing
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• 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 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 9/45541 Bare-metal, i.e. hypervisor runs directly on hardware
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

A system and method of emulating a shared storage device includes determining a storage unit identifier (SUID) associated with a first local storage device in a first node of a distributed computing system, updating a first path handler to intercept storage requests including the SUID and being made on the first node and forwarding the storage requests to drivers for an emulated shared storage device, associating a second local storage device in a second node of the distributed computing system with the SUID, updating a second path handler to intercept storage requests including the SUID and being made on the second node and forwarding the storage requests to the drivers for the emulated shared storage device, and intercepting storage requests including the SUID and being made on the second node and forwarding the storage requests to the drivers for the emulated shared storage device.

Claims

1. A method of emulating a shared storage device in a distributed computing system, the method comprising:

determining a storage unit identifier (ID) associated with a first local storage device in a first node of the distributed computing system;

updating a first path handler to intercept storage requests including the storage unit ID and being made on the first node and forwarding the storage requests to drivers for an emulated shared storage device;

associating a second local storage device in a second node of the distributed computing system with the storage unit ID;

updating a second path handler to intercept storage requests including the storage unit ID and being made on the second node and forwarding the storage requests to the drivers for the emulated shared storage device; and

intercepting storage requests including the storage unit ID and being made on the second node and forwarding the storage requests to the drivers for the emulated shared storage device.

2. The method of claim 1, further comprising forwarding the storage requests intercepted on the second node to a storage driver on the second node to access the second local storage device.

3. The method of claim 1, further comprising forwarding the storage requests intercepted on the second node to a storage driver on the first node to access the first local storage device.

4. The method of claim 1 wherein the first path handler is associated with a first path plugin on the first node and the second path handler is associated with the second storage driver.

5. The method of claim 1 wherein the first path handler is associated with a first hypervisor executing on the first node and the second path handler is associated with a second hypervisor executing on the second node.

6. The method of claim 1 wherein the storage requests intercepted on the second node originated from an application or an operating system executing on a first virtual machine being hosted on the second node.

7. The method of claim 6, further comprising migrating the first virtual machine from the first node to the second node.

8. The method of claim 1 wherein:

the storage requests intercepted on the second node include informational requests; and

the method further comprising the drivers of the emulated shared storage device responding to the informational requests by providing meta information consistent with a shared storage device.

9. The method of claim 1 wherein:

the storage requests intercepted on the second node include a read request; and

the method further comprising notifying a requesting driver of a failure when data associated with the read request is not stored on the second local storage device.

10. The method of claim 1 wherein:

the storage requests intercepted on the second node include a read request; and

the method further comprising forwarding the read request to a storage driver on the first node when data associated with the read request is not stored on the second local storage device.

11. The method of claim 10, further comprising:

accessing the first local storage device and reading the data associated with the read request; and

returning the data associated with the read request to the second path handler.

12. The method of claim 11, further comprising storing the data associated with the read request on the second local storage device.

13. The method of claim 1 wherein the drivers of the emulated shared storage device are located on a third node of the distributed computing system, the third node being different from the first node and the second node.

14. The method of claim 1 wherein the storage requests intercepted on the second node include write requests.

15. A system for emulating a shared storage device, the system comprising:

a distributed computing system comprising a first node and a second node;

the first node comprising a first local storage device associated with a storage unit identifier (ID) and a first processor for executing first storage requests;

a first path handler configured to intercept the first storage requests including the storage unit ID and being made by the first virtual machine and forward the first storage requests to drivers for an emulated shared storage device associated with the storage unit ID;

a second node comprising a second local storage device associated with the storage unit ID and a second processor for executing second storage requests; and

a second path handler configured to intercept the second storage requests including the storage unit ID and being made by the second virtual machine and forward the second storage requests to the drivers for the emulated shared storage device.

16. The system of claim 15, further comprising a network for coupling the first node to the second node.

17. The system of claim 15, wherein the drivers of the emulated shared storage device are distributed between the first node and the second node.

18. A non-transitory machine-readable medium comprising a first plurality of machine-readable instructions which when executed by processors associated with a cloud computing system cause the processors to perform a method comprising:

creating an emulated shared storage unit;

selecting a virtual machine (VM) being hosted on a source platform of the cloud computing system, the selected VM accessing a first local storage unit of the source platform, the first local storage unit being associated with a logical unit number (LUN);

selecting a target platform of the cloud computing system;

pausing the selected VM;

migrating the selected VM from the source platform to the target platform by moving a CPU state and a memory state of the selected VM from the source platform to the target platform;

resuming the selected VM on the target platform; and

directing storage operations associated with the LUN and being made by the selected VM on the target platform to the emulated shared storage unit.

19. The non-transitory machine-readable medium of claim 18 wherein creating the emulated shared storage unit comprises:

determining the LUN associated with the first local storage unit;

updating a first path plugin to intercept storage operations associated with the LUN and being made on the source platform and directing the storage requests to handlers for the emulated shared storage unit;

associating a second local storage unit of the target platform with the LUN; and

updating a second path plugin to intercept storage operations associated with the LUN and being made on the target platform and directing the storage requests to the handlers for the emulated shared storage unit.

20. The non-transitory machine-readable medium of claim 18, further comprising a second plurality of machine-readable instructions which when executed by the one or more processors cause the one or more processors to perform a method comprising intercepting storage operations associated with the LUN and being made by the selected VM and directing them to the handlers for the emulated shared storage unit.

21. The non-transitory machine-readable medium of claim 20 wherein:

the storage operations intercepted on the target platform include a read operation; and

the non-transitory machine-readable medium further comprises a third plurality of machine-readable instructions which when executed by the one or more processors cause the one or more processors to perform a method comprising;

reading the data from the second local storage unit when data associated with the read operation is stored on the second local storage unit;

reading the data from the first local storage unit when the data associated with the read operation is not stored on the second local storage unit; and

returning the read data to the selected VM.