US 2006/0085609 A1Published application

Remote copy system

AssigneeHitachi, Ltd.

InventorsKenta Ninose, Hiroshi Arakawa, Takashige Iwamura, Yoshihiro Asaka, Yusuke Hirakawa

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Abstract

To provide a computer system constituting a multitarget array and utilizing a remote copy technique for backing up data, in which when a failure occurs in a primary site, a new pair is formed between remaining two secondary sites without copying all data. A first secondary site is associated with the primary site by synchronous remote copy. A second secondary site is associated with the primary site by asynchronous remote copy. A storage system of the first secondary site includes a difference bitmap indicating an area to which data has been written from a host computer. When a failure occurs in a host computer of the primary site, only data of an area indicated by the difference bitmap is transferred to a storage system of the second secondary site.

Claims12

Dependent claims

A computer system, comprising:

a first storage system that is coupled to a first host computer;
a second storage system that is coupled to a second host computer and the first storage system;
and
a third storage system that is coupled to the first storage system and the second storage system, wherein:
the first storage system stores data sent from the first host computer,
transfers the data sent from the first host computer to the second storage system by synchronous remote copy, and
transfers the data sent from the first host computer to the third storage system by asynchronous remote copy;
and
the second storage system
comprises a first difference bitmap,
updates a bit of the first difference bitmap corresponding to an area to which the data has been written from the second host computer after data is written from the second host computer to the second storage system, and
transfers the data stored in the area corresponding to the updated bit of the first difference bitmap to the third storage system.

9 more elements

A computer system, comprising:

a first storage system that is coupled to a first host computer;
a second storage system that is coupled to a second host computer and the first storage system;
and
a third storage system that is coupled to the first storage system and the second storage system, wherein:
after receiving an instruction to write data from the first host computer, the first storage system
stores an update order identifier for identifying the order of writing the data and the data as a first journal record,
transfers the update order identifier and the data to the second storage system by the synchronous remote copy, and
transfers the first journal record to the third storage system by the asynchronous remote copy;
the second storage system
stores the update order identifier and the data that have been transferred from the first storage system as a second journal record,
stops transferring data between the first storage system and the second storage system by the synchronous remote copy,
stores, after data is written from the second host computer, the written data and an update order identifier that follows the update order identifier that has been transferred from the first storage system as the second journal record, and
transfers the second journal record to the third storage system;
and
the third storage system
receives the first journal record that has been transferred from the first storage system,
further receives the second journal record that has been transferred from the second storage system, and
stores the data of the first journal record and the data of the second journal record that have been received, in an order of the update order identifiers.

15 more elements

A control method for a computer system,

the computer system comprising:
a first storage system that is coupled to a first host computer;
a second storage system that is coupled to a second host computer and the first storage system, and comprises a first difference bitmap;
and
a third storage system that is coupled to the first storage system and the second storage system,
the control method comprising the steps of:
transferring data written from the first host computer to the second storage system by synchronous remote copy;
further transferring the data written from the first host computer to the third storage system by asynchronous remote copy;
writing data sent from the second host computer to the second storage system;
updating a bit of the first difference bitmap corresponding to an area to which the data has been written from the second host computer;
and
transferring the data stored in the area corresponding to the updated bit of the first difference bitmap from the second storage system to the third storage system.

9 more elements

Dependencies are inferred from the claim text.