STORAGE DEVICE AND DATA MIGRATION METHOD

• US 20150324418A1
• Filed: 01/17/2013
• Published: 11/12/2015
• Est. Priority Date: 01/17/2013
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: SHIMOZONO, Norio, TATSUMI, Ryosuke, NISHINA, Tadato
• Granted Patent: US 9,977,813 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: G06F 16/2365 Ensuring data consistency and integrity
• CPC Class Codes: G06F 16/955 using information identifiers, e.g. uniform resource locators [URL]
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

As a method for migrating data of a volume adopting a snapshot function to a new storage system, in order to perform migration without depending on a method for compressing snapshot data of a migration source storage system, and without stopping transmission and reception of data between the host computer and the storage system, at first, after migrating data of a volume being the source of snapshot (PVOL), migration is performed sequentially from newer generations. At this time, migration target data of each SVOL is all the data within the migration source storage system. The SVOL data copied to a migration destination storage is compared with one-generation-newer SVOL data within the migration destination storage system, and based on the comparison result, a difference management information is created. If there is difference, a VOL allocation management table is updated, and difference data is stored in the area allocated within the pool.

Claims

1. A storage system coupled to another storage system and managing both current data and data of a certain point of time in the past for n generations (n being an integer of 2 or more), the storage system comprising:

a controller; and

at least one storage device;

wherein

the controller comprises

acquiring, from the other storage system, at least a data of generation n of a certain point of time and a data of generation n−

1 at a point of time in the past than generation n;

determining whether there is any difference data between the data of generation n and the data of generation n−

1; and

generating a difference information of data of generation n−

1 with respect to generation n based on the determination result, and storing the same in the storage device.

2. The storage system according to claim 1, wherein

the controller further comprises:

after determining whether there is any difference data between the data of generation n and the data of generation n−

1;

determining whether there is any difference data between the data of generation n−

1 and the data of generation n−

2 at a point of time in the past compared to generation n−

1 (n being an integer of 3 or greater) acquired from the other storage system; and

generating a difference information of data of generation n−

2 with respect to generation n−

1 based on the determination result, and storing the same in the storage device.

3. The storage system according to claim 1, wherein the controller acquires data of a current state as data of generation n+1 which is newer than generation n.

4. The storage system according to claim 1, wherein

the data of generation n (n being an integer of 3 or greater) is the data of the current state;

and

the controller further comprises;

acquiring a data of generation n−

2 of a point of time in the past than generation n−

1;

determining whether there is any difference data between the data of generation n and the data of generation n−

2; and

generating a difference information of data of generation n−

2 with respect to generation n based on the determination result, and storing the same in the storage device.

5. The storage system according to claim 1, wherein

the controller comprises:

providing a pool area in a storage area provided by the storage device;

regarding the data of generation n−

1, referring to the acquired data of generation n as for the same data as generation n; and

as for the data that differs from generation n, performing management so as to store the data in the pool area based on the difference information, and refer to the stored data.

6. The storage system according to claim 5, wherein

the controller comprises:

during acquisition of data from the other storage system, if an update request regarding the data being the target of acquisition is received, executing data update based on the update request regarding the already acquired data; and

not executing the data update based on the update request regarding non-migrated data.

7. A storage system coupled to another storage system and managing both current data and data of a certain point of time in the past for n generations (n being an integer of 3 or more), the storage system comprising:

a controller; and

at least one storage device;

wherein

the controller comprises

acquiring, from the other storage system, current information data which is a data of generation n, data of generation n−

1 at a point of time in the past than generation n, and data of generation n−

m at a point of tine in the past than generation n−

1 (m being an integer of 2 or more, and n>

m); and

determining whether there is any data from generation n to generation n−

m that corresponds to the data of generation n−

m+1 or newer, generating information showing that data is shared with the data of the generation closest to n from the data that correspond, and storing the same in the storage device.

8. A data migration method for migrating data from a first storage system managing current data and data of a certain point of time in the past for n generations (n being an integer of 2 or more) to a second storage system, the method comprising:

a step of acquiring a data of generation n of a certain point of time from the first storage system;

a step of acquiring a data of generation n−

1 at a point of time in the past than generation n from the first storage system, and determining whether there is any difference data by comparison with the data of generation n; and

a step of generating a difference information of data of generation n−

1 with respect to generation n if there is difference data, and storing the same.

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

after the step of determining whether there is any difference data between the data of generation n and the data of generation n−

1, a step of determining whether there is any difference data between the data of generation n−

1 and the data of generation n−

2 at a point of time in the past compared to generation n−

1 (n being an integer of 3 or greater) acquired from the first storage system; and

a step of generating a difference information of data of generation n−

2 with respect to generation n−

1 if there is difference data, and storing the same.

10. The data migration method according to claim 8, further comprising:

a step of acquiring data of a current state as a data of generation n+1 newer than generation n.

11. The data migration method according to claim 8, wherein the data of generation n (n being an integer of 3 or greater) is set as the data of the current state;

the method further comprising;

a step of acquiring from the first storage system a data of generation n−

2 of a point of time in the past than generation n−

1;

a step of determining whether there is any difference data by comparing the data of generation n and the data of generation n−

2; and

a step of generating a difference information of data of generation n−

2 with respect to generation n if there is difference data, and storing the same.

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

a step of storing data from the data of generation n−

1 that differs from the data of generation n based on the difference information in a pool area provided in the second storage device.

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

during acquisition of data from the first storage system, if an update request regarding the data being the target of acquisition is received, only executing data update based on the update request regarding the already migrated data and not executing data update regarding non-migrated data.