Data migration method and a data migration apparatus

• US 7,237,079 B2
• Filed: 09/30/2005
• Issued: 06/26/2007
• Est. Priority Date: 02/26/2004
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Kaneda, Yasunori, Fujita, Takahiro
• Primary Examiner(s): Peugh; Brian R.
• Application Number:
  US11/239,129
• Publication Number:
  US 20060026373A1
• Time in Patent Office: 634 Days
• Field of Search: None
• US Class Current: 711/162
• CPC Class Codes: G06F 3/0622 in relation to access
• CPC Class Codes: G06F 3/0649 Lifecycle management
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

The management computer 600 copies data in the volume 111 within the storage device 100A to the volume 115 within the storage device 100B. Upon completion of copy processing, the volume 115 is set to write protect. Then, the data in the volume 111 is read from the storage device 100A, and the data in the volume 115 is also read from the storage device 100B, to compare the two data items. Only when the data items agree with each other, setting of FC switch 400 is changed, and a target of the host computer 500 is switched from the storage device 100A to the storage device 100B.

Therefore, it is possible to detect or prevent an illegal data modification in the course of data copying from the source volume to the destination volume.

Claims

1. A data migration method which carries out data migration from a first storage device to a second storage device in a computer system, comprising a host computer, said first storage device and said second storage device which provide volumes to said host computer, a switch which establishes connection among said host computer, said first storage device and said second storage device, and a data migration apparatus, wherein,

said data method comprising the steps of:

(a) providing to said second storage device, a request for creating a destination volume having a size identical to the size of a source volume that is provided by said first storage device;

(b) carrying out a data copy processing which copies the data stored in said source volume, which data is comprised of a plurality of data blocks each having a predetermined data length, to said destination volume, by repeating a processing with respect to data in said source volume from top to bottom so that all of the data in the source volume is copied to the destination volume one data block at a time until all of the plurality of data blocks comprising said data stored in said source volume are copied to said destination volume, under a condition that a write complete notification as to data immediately before said data is received from said second storage device, said processing including, to read out data of a predetermined length from said source volume, calculate a write address in said destination volume on the basis of a total data length of the data read out so far from said source volume, and to provide to said second storage device a request for writing the data together with a designation of the write address thus calculated; and

(c) providing a connection switching request to said switch and carrying out switching of a target of said host computer, from said first storage device to said second storage device, and

wherein said second storage device performs the steps of;

(d) creating said destination volume in accordance with the request for creating said destination volume received from said data migration apparatus,

(e) comparing the write address designated by the request for writing the data to said destination volume, which is received from said data migration apparatus, with a reserved write address of a new data in said destination volume determined by the total data length of data already-written in said destination volume, and

(f) executing the write request and issuing a write complete notification to said data migration apparatus if the two addresses equal to each other, and

(g) repeating steps (e) and (f) until all of the data blocks comprising the data of the source volume have been copied to the destination volume.

2. A data migration method according to claim 1, wherein,

if the two addresses do not equal to each other as a result of comparison, said second storage device does not execute the write request and issues an error notification to said data migration apparatus, and said data migration apparatus terminates said data copy processing.

3. A storage device to which data in a source volume, which data is comprised of a plurality of data blocks each having a predetermined data length, is copied by a data migration apparatus so that all of the data in the source volume is copied to the destination volume one data block at a time until all of the plurality of data blocks comprising said data stored in said source volume are copied to said destination volume, comprising:

volume creation unit which creates a destination volume having a size identical to said source volume, according to a volume creation request received from said data migration apparatus, and

a write request processing unit which compares a write address designated by a write request for writing the data to said destination volume, which is received from said data migration apparatus, with a reserved write address of a new data to said destination volume determined by a total data length of data already-written in said destination volume, and if the two addresses equal to each other, executes the write request and issues a write complete notification to said data migration apparatus, and if the two addresses do not equal to each other, issues an error notification to said data migration apparatus without executing the write request, wherein the write request processing unit repeats comparing the write address, executing the write request and issuing a write complete notification for each data block, one block at a time, until the plurality of data blocks which comprise the data stored in the source volume have been copied to the destination volume, unless an error notification is issued.

4. A computer readable recording medium which stores a program allowing a storage device to copy data in a source volume to a destination volume, which data is comprised of a plurality of data blocks each having a predetermined data length, according to an instruction from a data migration apparatus, so that all of the data in the source volume is copied to the destination volume one data block at a time until all of the plurality of data blocks comprising said data stored in said source volume are copied to said destination volume, wherein,

said program comprises:

code that creates the destination volume having a size identical to said source volume, according to a volume creation request received from said data migration apparatus, and

code that compares a write address designated by a request for writing the data to said destination volume, which is received from said data migration apparatus, with a reserved write address of a new data to said destination volume determined by a total data length of data already-written in said destination volume, and if the two addresses equal to each other, executes the write request and issues a write complete notification to said data migration apparatus, and if the two addresses do not equal to each other, issues an error notification to said data migration apparatus without executing the write request, wherein the code repeats comparing the write address, executing the write request and issuing a write complete notification for each data block, one block at a time, until the plurality of data blocks which comprise the source volume have been copied to the destination volume, unless an error notification is issued.