AUTOMATED ON-LINE CAPACITY EXPANSION METHOD FOR STORAGE DEVICE

• US 20090043982A1
• Filed: 10/03/2008
• Published: 02/12/2009
• Est. Priority Date: 07/05/2001
• Status: Active Grant

• Current Assignee: Kouji Arai, Manabu Kitamura, Yoshiki Kano
• Original Assignee: Kouji Arai, Manabu Kitamura, Yoshiki Kano
• Inventors: Kitamura, Manabu, Arai, Kouji, KANO, Yoshiki
• Granted Patent: US 7,930,474 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• 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 3/0644 Management of space entities, e.g. partitions, extents, pools
• 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 volume provider unit in a computer system that detects a logical block address of a read or write I/O accessing a logical volume of a storage device from a host. According to the logical block address fetched, a storage domain of the logical volume is dynamically expanded. Moreover, the storage domain of the logical volume is reduced or expanded according to an instruction of logical volume capacity reduction or expansion from a host commander part to a volume server.

Claims

1. A storage system comprising:

a plurality of logical volumes accessed from a computer;

a plurality of disks including a plurality of physical storage areas; and

a controller coupled to said plurality of disks and said computer;

wherein, in response to a write request to a first logical volume of said plurality of logical volumes from said computer, if a physical storage area to write data of said write request is allocated to said first logical volume, said controller writes said data of said write request into said allocated physical storage areas,

wherein, in response to a write request, if a physical storage area to write data of said write request is not allocated to said first logical volume, said controller allocates a part of said physical storage areas to said first logical volume, and writes said data into said part of said physical storage areas, and

wherein said controller monitors a capacity of physical storage areas which are not allocated to said plurality of logical volumes.

2. The storage system according to claim 1,

wherein said controller calculates a ratio from the number of physical storage areas in use and the total number of said plurality of physical storage areas, and determines whether said ratio is equal to or more than a predetermined ratio, and

wherein if said ratio is equal to or more than said predetermined ratio, said controller makes a request to add a physical storage area.

3. The storage system according to claim 1, wherein said controller comprises:

an Input/Output detector accepting an Input/Output request, including a write request and/or a read request, to said plurality of logical volumes from said computer;

an Input/Output processor performing an Input/Output process according to said Input/Output request;

a capacity controller allocating a physical storage area to said plurality of logical volumes,

a segment manager managing said physical storage areas; and

a physical and logical address manager managing a relationship between physical address and logical address.

4. The storage system according to claim 3, wherein said controller further comprises:

a physical and logical management table residing in said physical and logical address manager, said physical and logical management table containing information related to at least of a logical unit number, a segment number, a starting logical unit number logical block address, and an ending logical unit number logical block address.

5. The storage system according to claim 1,

wherein if said controller receives said write request from said computer, the controller detects a logical block address in said first logical volume and determines whether said logical block address information exists in said allocated physical storage area or not.

6. The storage system according to claim 1, further comprising:

a segment management table which stores a disk number for identifying each of the disks, a segment number assigned to each of the physical storage areas, a start logical block address which is a start address of the physical storage area, a size of the physical storage area, and a state indicating whether or not the physical storage area is in use, associated with each other; and

a physical and logical management table which stores, for each of the plurality of logical volumes, a logical unit number for identifying each logical volume, the segment number, a start address of each logical volume, and an end address of each logical volume, associated with each other,

wherein the controller selects the segment number to be accessed and the start address of the corresponding logical volume from the physical and logical management table, and calculates the disk number and the physical address of the disk to be accessed by an I/O request using the selected segment number and the segment management table.

7. The storage system according to claim 6,

wherein the controller checks rate of the physical storage areas with in-use state on the segment management table, and indicates necessity of an addition of the disk if the rate reaches a predetermined value, and

wherein when a new disk is added to the storage system, the controller checks a capacity of the added disk, and adds to the segment management table information on the added disk.

8. A method for storing data in a storage system, said storage system comprising a plurality of logical volumes accessed from a computer, a plurality of disks including a plurality of physical storage areas, and a controller coupled to said plurality of disks and said computer, said method comprising:

in response to a write request to a first logical volume of said plurality of logical volumes from said computer, if a physical storage area to write data of said write request is allocated to said first logical volume, writing by said controller said data of said write request into said allocated physical storage areas;

in response to a write request, if a physical storage area to write data of said write request is not allocated to said first logical volume, allocating by said controller a part of said physical storage areas to said first logical volume, and writing said data into said part of said physical storage areas; and

monitoring by said controller a capacity of physical storage areas which are not allocated to said plurality of logical volumes.

9. The method according to claim 8, further comprising:

calculating by said controller a ratio from the number of physical storage areas in use and the total number of said plurality of physical storage areas, and determining by said controller whether said ratio is equal to or more than a predetermined ratio; and

if said ratio is equal to or more than said predetermined ratio, making a request, by said controller, to add a physical storage area.

10. The method according to claim 8, wherein said controller comprises an Input/Output detector, an Input/Output processor, a capacity controller, a segment manager, and a physical and logical address manager, said method further comprising:

accepting, by said Input/Output detector, an Input/Output request, including a write request and/or a read request, to plurality of logical volumes from said computer;

performing, by said Input/Output processor, an Input/Output process according to said Input/Output request;

allocating, by said capacity controller, a physical storage area to said plurality of logical volumes;

managing, by said segment manager, said physical storage areas; and

managing, by said physical and logical address manager, a relationship between physical address and logical address.

11. The method according to claim 8, further comprising:

if said controller receives said write request from said computer, detecting by the controller a logical block address in said first logical volume, and determining by the controller whether said logical block address information exists in said allocated physical storage area or not.

12. The method according to claim 8, further comprising:

preparing a segment management table which stores a disk number for identifying each of the disks, a segment number assigned to each of the physical storage areas, a start logical block address which is a start address of the physical storage area, a size of the physical storage area, and a state indicating whether or not the physical storage area is in use associated with each other;

preparing a physical and logical management table which stores, for each of the plurality of logical volumes, a logical unit number for identifying each logical volume, the segment number, a start address of each logical volume, and an end address of each logical volume, associated with each other; and

selecting, by said controller, the segment number to be accessed and the start address of the corresponding logical volume from the physical and logical management table, and calculating the disk number and the physical address of the disk to be accessed by an I/O request using the selected segment number and the segment management table.

13. The method according to claim 12, further comprising:

checking, by said controller, rate of the physical storage areas with in-use state on the segment management table, and indicating necessity of an addition of the disk if the rate reaches a predetermined value, and

when a new disk is added to the storage system, checking, by said controller, a capacity of the added disk and adding to the segment management table information on the added disk.