Storage virtualization system and methods

• US 20050125593A1
• Filed: 01/05/2005
• Published: 06/09/2005
• Est. Priority Date: 01/11/2001
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Yotta Yotta Incorporated (Dell Technologies Inc.)
• Inventors: Lake, Brian, Karpoff, Wayne
• Granted Patent: US 7,577,817 B2
• Time in Patent Office: Days
• US Class Current: 711/4
• CPC Class Codes: G06F 12/08 in hierarchically structured memory systems, e.g. virtual memory systems
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Storage virtualization systems and methods that allow customers to manage storage as a utility rather than as islands of storage which are independent of each other. A demand mapped virtual disk image of up to an arbitrarily large size is presented to a host system. The virtualization system allocates physical storage from a storage pool dynamically in response to host I/O requests, e.g., SCSI I/O requests, allowing for the amortization of storage resources-through a disk subsystem while maintaining coherency amongst I/O RAID traffic. In one embodiment, the virtualization functionality is implemented in a controller device, such as a controller card residing in a switch device or other network device, coupled to a storage system on a storage area network (SAN). The resulting virtual disk image that is observed by the host computer is larger than the amount of physical storage actually consumed.

Claims

1. A method of dynamically mapping addresses between a virtual disk address and one or more physical block addresses for a storage system in response to a write operation requested by a host system, the method comprising:

receiving a write request from a host, said write request including a virtual memory address and one or more blocks of data;

determining whether memory space in the storage system has been allocated for the one or more blocks of data based on the virtual memory address;

if it is determined that memory space has been allocated, completing the write operation to the allocated memory space; and

if it is determined that no memory space has been allocated;

automatically allocating memory space in the storage system for the one or more blocks of data; and

completing the write operation to the allocated memory space.

2. The method of claim 1, wherein determining includes determining whether a mapping table includes a link between the virtual address and one or more physical block addresses of the storage system.

3. The method of claim 1, wherein automatically allocating includes automatically updating a mapping table to include an entry linking the virtual address and one or more physical block addresses of the storage system.

4. The method of claim 1, wherein if it is determined that no memory space has been allocated, the method further comprises:

determining the number of blocks of memory space in the storage system to be allocated.

5. The method of claim 4, wherein the number of blocks allocated is greater than the number of data blocks included with the write request.

6. The method of claim 1, wherein the storage system includes a plurality of storage devices.

7. A method of dynamically mapping addresses between a virtual disk address and one or more physical block addresses for a storage system in response to a request from a host system to perform an operation on the storage system, the method comprising:

receiving a request from a host to perform an operation on one or more blocks of the storage system, said request including a virtual memory address;

determining from a mapping table whether memory space in the storage system has been allocated for the virtual memory address;

if it is determined that memory space has been allocated, completing the operation on the allocated memory space; and

if it is determined that no memory space has been allocated;

automatically allocating memory space in the storage system for the virtual address; and

completing the operation on the allocated memory space.

8. The method of claim 7, wherein the operation is a read operation, and wherein if it is determined that memory space has been allocated, completing the operation includes retrieving the data from the allocated memory space.

9. The method of claim 8, wherein the operation is a read operation, and wherein if it determined that no memory space has been allocated, completing the operation includes returning a default formatted page without retrieving any data from the storage system.

10. The method of claim 7, wherein the operation is a write operation and wherein the request includes one or more blocks of data to be written to the storage system.

11. The method of claim 10, wherein if it is determined that no memory space has been allocated, the method further comprises:

determining the number of blocks of memory space in the storage system to be allocated.

12. The method of claim 11, wherein the number of blocks allocated is greater than the number of data blocks included with the write request.

13. The method of claim 7, wherein determining includes determining whether a mapping table includes a link between the virtual address and one or more physical block addresses of the storage system.

14. The method of claim 7, wherein automatically allocating includes automatically updating a mapping table to include an entry linking the virtual address and one or more physical block addresses of the storage system.

15. The method of claim 7, wherein the storage system includes a plurality of storage devices.