Copying method between logical disks, disk-storage system and its storage medium

• US 6,732,245 B2
• Filed: 09/30/2002
• Issued: 05/04/2004
• Est. Priority Date: 09/30/1999
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kaiya, Norikazu, Onda, Yasuhiro, Kato, Tadaomi
• Primary Examiner(s): Nguyen, Hiep T.
• Assistant Examiner(s): Dinh, Ngoc V
• Application Number:
  US10/259,506
• Publication Number:
  US 20030028737A1
• Time in Patent Office: 582 Days
• Field of Search: 711/114, 711/162, 711/112, 711/161
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1466 to make the backup process non-disruptive
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

A copying method, disk storage system, and storage medium for copying data from one logical disk to another logical disk, making possible immediate access, in response to a copy command. Copying from a first logical disk to a second logical disk is performed for each area in a copy range, and where is an access to either logical disk, copying is interrupted. When performing update access of an uncopied area in the first logical disk, the area is copied from the first logical disk to a second logical disk, and then the uncopied area is updated. When performing reference access of an uncopied area in the second logical disk, the corresponding area in the first logical disk is referenced. When performing update access of an uncopied area in the second logical disk, that area in the second logical disk is updated, and copying is prohibited. In this way, it is possible to access the first and second logical disks while copying is in progress, and it is possible to immediately notify a host, upon receipt of a copy instruction, that a copying has been completed.

Claims

1. An accessing method of logical disks comprising:

first accessing a cache memory to store part of data of the logical disks that is staged from the logical disks according to an access request from a host;

second accessing a designated logical disk when not finding a target data in the cache memory by said first accessing and staging said target data from said designated logical disk to said cache memory in response to said access request from said host; and

copying data from a copy-source logical disk to a copy-destination logical disk according to a copy instructions from the host;

wherein the copying comprising;

performing said staging to stage data of a copy target area of the copy-source logical disk to a first cache memory to store part of data of the copy-source logical disk;

transferring the staged data in the first cache memory to a second cache memory to store part of data of the copy-destination logical disk;

writing the transferred data in the second cache memory to the copy-destination logical disk,

referencing control information that indicates a copying condition of the each of the areas of the copy-source logical disk in a first bitmap and determining a next copy area according to the reference result,

updating the control information in the first bitmap and a second bitmap that indicates a copying condition of the each of the areas of the copy-destination disk,

interrupting said copying in response to the access request from the host; and

allowing accesses to the copy-source logical disk by referring the first bitmap when said access request is a request for the copy-source logical disk and to the copy-destination logical disk by referring the second bitmap when said request for the copy-destination logical disk during said copying.

2. The accessing method of claim 1, wherein said allowing of access includes:

referencing the first bitmap, copying the target access area of the copy-source logical disk to the copy-destination logical disk and then updating the target access area of the copy-source logical disk when the access request is a request for updating an uncopied area of the copy-source logical disk;

referencing the second bitmap, staging the target access area of the copy-source logical disk to the first cache memory and transferring the staged data from the first cache memory to the second cache memory when the access request is a request for referencing an uncopied area of the copy-destination logical disk; and

referencing the second bitmap, writing the update data to the second cache memory, updating the target access area of the copy-destination logical disk and prohibiting copying of data from the copy-source logical disk to the target area when the access request is for the updating of an uncopied area of said copy-destination logical disk.

3. A disk storage system comprising:

at least one physical disk including a plurality of logical disks;

a cache memory to store part of data of the logical disks that is staged from the logical disks; and

a disk controller to search the cache memory whether a target data is stored or not in the cache memory and to access a designated logical disk and stage said target data from said designated logical disk to said cache memory in response to said access request from a host when not finding a target data in the cache memory by said search according to an access request from said host,

wherein the cache memory comprises a first cache memory to store part of data of the copy-source logical disk and a second cache memory to store part of data of the copy-destination logical disk,

and wherein the disk controller performs said staging to stage data of a copy target area of the copy-source logical disk to the first cache memory to store part of data of the copy-source logical disk, transfers the staged data in the first cache memory to the second cache memory to store part of data of the copy-destination logical disk, and writes the transferred data in the second cache memory to the copy-destination logical disk,

a first bit map that stores control information that indicates a copying condition of the each of the areas of the copy-source logical disk and a second bit map that stores control information that indicates a copying condition of the each of the areas of the copy-destination logical disk,

and wherein the disk controller references the control information that indicates a copying condition of the each of the areas of the copy-source logical disk in a first bitmap and determines a next copy area according to the reference result and updates the control information in the first bitmap and the second bitmap that indicates a copying condition of the each of the areas of the copy-destination disk,

and wherein further the disk controller interrupts said copying in response to the access request from the host, and allows accesses to the copy-source logical disk by referring the first bitmap when said access request is a request for the copy-source logical disk and to the copy-destination logical disk by referring the second bitmap when said request for the copy-destination logical disk during said copying.

4. The disk storage system of claim 3,

and wherein the disk controller

references the first bitmap, copies the target access area of the copy-source logical disk to the copy-destination logical disk and then updates the target access area of the copy-source logical disk when the access request is a request for updating an uncopied area of the copy-source logical disk;

references the second bitmap, staging the target access area of the copy-source logical disk to the first cache memory and transfers the staged data from the first cache memory to the second cache memory when the access request is a request for referencing an uncopied area of the copy-destination logical disk; and

references the second bitmap, writing the update data to the second cache memory, updates the target access area of the copy-destination logical disk and prohibits copying of data from the copy-source logical disk to the target area when the access request is for the updating of an uncopied area of said copy-destination logical disk.