Storage virtualization system and methods

• US 7,577,817 B2
• Filed: 01/05/2005
• Issued: 08/18/2009
• Est. Priority Date: 01/11/2001
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Lake, Brian, Karpoff, Wayne
• Primary Examiner(s): Elmore; Reba I
• Application Number:
  US11/031,628
• Publication Number:
  US 20050125593A1
• Time in Patent Office: 1,686 Days
• Field of Search: 711/114, 711/170, 711/200, 711/209, 711/203, 711/206
• US Class Current: 711/206
• 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 dynamically allocated from a storage system shared by one or more virtual disks 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 of more blocks of data;

determining whether memory space in the storage system has not been allocated for the one of more blocks of data based on the virtual memory address;

if so, automatically and dynamically allocating memory space from a pool of available memory space in the storage system for the one or more blocks of data;

wherein automatically and dynamically allocating memory space from the pool of available memory space in the storage system for the one or more blocks of data comprises;

based upon detecting that storage has not been allocated for a physical block address and in response to receiving the write request, automatically and dynamically allocating physical block addresses from a pool of available physical block addresses in the storage system for the one or more blocks of data;

wherein, upon detecting that storage has not been allocated for the physical block address;

comparing the one or more blocks of data with a default formatted block value indicating a predefined data size associated with the storage system;

when the one or more blocks of data matches the default formatted block, completing the write operation to the physical block addresses; and

when the one or more blocks of data does not match the default formatted block detecting a region of continuous blocks associated with the storage system, dynamically allocating region of continuous blocks associated with the storage system for the one or more blocks of data, and completing the write operation to the dynamically allocated physical block addresses; and

if the allocated memory space has been freed after the write operation, returning the memory space that has been freed to the pool of available 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 the storage system includes a plurality of storage devices.

4. The method of claim 1, wherein the pool of available memory space is shared by the one or more virtual disks.

5. The method of claim 1, wherein

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

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

determining whether memory space in the storage system has not been allocated for the one of more blocks of data based on the virtual memory address comprises;

in response to receiving the write request, querying a data structure that maintains data allowing translation of a virtual block address to a physical block address, and

based upon the query, detecting if storage has been allocated for the physical block address based on the virtual block address; and

if the allocated memory space has been freed after the write operation, returning the memory space that has been freed to the pool of available memory space comprises;

if the allocated physical block addresses has been freed after the write operation, returning the physical block addresses that has been freed to the pool of available physical block addresses of the storage system.

6. 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.

7. The method of claim 6, wherein the mapping table is shared by a plurality of network controller devices and kept coherent among said controller devices.

8. 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.

9. The method of claim 8, wherein the number of blocks allocated is greater than the number of data blocks included with the write request.