Data migration method and a data migration apparatus

• US 20060026373A1
• Filed: 09/30/2005
• Published: 02/02/2006
• Est. Priority Date: 02/26/2004
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Takahiro Fujita, Yasunori Kaneda
• Inventors: Kaneda, Yasunori, Fujita, Takahiro
• Granted Patent: US 7,237,079 B2
• Time in Patent Office: Days
• 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 migration apparatus comprising the steps of:

invoking 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;

carrying out a data copy processing which copies the data stored in said source volume to said destination volume, by repeating a processing with respect to data in said source volume from top to bottom, 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 invoke to said second storage device a request for writing the data together with a designation of the write address thus calculated; and

invoking 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

said second storage device comprising the steps of;

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

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 already-written in said destination volume, and

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

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 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 switch issues a connection notification to said data migration apparatus when a new computer is connected;

and

said data migration apparatus invokes a request for creating a destination volume having a size identical to a source volume provided by said first storage device, allowing said second storage device to create said destination volume,

carries out a data copy processing which stores data corresponding to data in the source volume, into the destination volume, and

suspends said data copy processing upon receipt of said connection notification from said switch during said data copy processing.

4. A storage device to which data in a source volume is copied by a data migration apparatus, comprising:

a 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 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.

5. A data migration apparatus which carries out data migration from a first storage device to a second storage device, comprising:

a volume creation unit which invokes a request for creating a destination volume having a size identical to a source volume provided by said first storage device, allowing said second storage device to create said destination volume;

a connection notification receive unit which receives a connection notification of a new computer from a switch connecting a host computer, said first storage device and said second storage device; and

a data copy unit which carries out a data copy processing which stores the data corresponding to data stored in said source volume, into said destination volume, and suspends said data copy processing upon receipt of said connection notification by said connection notification receive means during said data copy processing.

6. A computer readable recording medium which stores a program allowing a storage device to copy data in a source volume, according to an instruction from a data migration apparatus, wherein,

said program comprises:

code that 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

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 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.

7. A computer readable recording medium which allows a data migration apparatus to carry out a data migration from a first storage to a second storage, wherein said program comprises:

code that invokes 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, allowing said second storage device to create said destination volume;

code that receives a connection notification of a new computer from a switch connecting a host computer, said first storage device and said second storage device; and

code that carries out data copy processing which stores data corresponding to data stored in said source volume, into said destination volume, and suspends said data copy processing upon receipt of said connection notification by said connection notification receive means during said data copy processing.