Method, system, apparatus, and computer-readable medium for improving disk array performance

• US 7,802,063 B1
• Filed: 03/15/2010
• Issued: 09/21/2010
• Est. Priority Date: 06/10/2005
• Status: Active Grant

• Current Assignee: AmZetta Technologies, LLC (American Megatrends International, LLC)
• Original Assignee: American Megatrends Incorporated
• Inventors: Chatterjee, Paresh, Narayanan, Ajit, Muthirisavenugopal, Vijayarankan
• Primary Examiner(s): Elmore; Stephen C
• Application Number:
  US12/723,861
• Time in Patent Office: 190 Days
• Field of Search: 711/156, 711/112, 711/114, 711/170, 711/221, 707/781, 707/802, 707/812, 714/5, 714/6, 714/7
• US Class Current: 711/156
• CPC Class Codes: G06F 11/1092 Rebuilding, e.g. when physically replacing a failing disk
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 2211/104 Metadata, i.e. metadata associated with RAID systems with parity
• CPC Class Codes: G06F 2211/1059 Parity-single bit-RAID5, i.e. RAID 5 implementations
• CPC Class Codes: G06F 2212/262 configured as RAID
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0632 by initialisation or re-initialisation of storage systems
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

A method, system, apparatus, and computer-readable medium are provided for improving storage in a disk array are provided. According to aspects of the invention, a redundant disk array is combined with a mechanism for thin provisioning of the array. Thin provisioning refers to a process of allocating physical capacity to logical volumes on an as-needed basis. Data structures containing a mapping between the logical location of stored data and its actual location on a physical device are maintained. Through the use of the thin provisioning mechanism, physical storage space can be allocated sequentially, regardless of the order of logical writes. In this manner, the data stored on the array grows in a linear manner. The data structures maintained by the thin provisioning mechanism can be used to identify the portions of a device or an array that have been previously written. This information allows redundant arrays, such as RAID arrays, to perform initialization, rebuild, and data migration operations only on portions that been written, and not on areas that have not been utilized by a higher layer.

Claims

1. A method for writing metadata to a mass storage array comprising two or more mass storage devices, the array being divided into stripes having two or more blocks, the method comprising:

maintaining metadata relating to the array in a memory;

creating changed metadata from existing metadata stored on the array;

reading a parity block from a stripe of the array where the changed metadata is to be stored;

calculating a new parity for the stripe using only the existing metadata, the changed metadata, and the parity read from the array;

storing the changed metadata on the array; and

storing the new parity on the array.

2. A computer-readable medium having computer-readable instructions stored thereon which, when executed, cause a computer to perform the method of claim 1.

3. A computer-controlled apparatus capable of performing the method of claim 1.