COMPUTER SYSTEM AND METHOD OF CONTROLLING COMPUTER SYSTEM

• US 20140173017A1
• Filed: 12/03/2012
• Published: 06/19/2014
• Est. Priority Date: 12/03/2012
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takagi, Takumi, Chikusa, Takashi
• Granted Patent: US 9,055,044 B2
• Time in Patent Office: Days
• US Class Current: 709/213
• CPC Class Codes: G06F 12/0873 Mapping of cache memory to specific storage devices or parts thereof
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0635 by changing the path, e.g. traffic rerouting, path reconfiguration
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0685 Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04N 21/23116 involving data replication, e.g. over plural servers synchronization of replicated data G06F11/1658; error detection or correction by means of data replication G06F11/2053; replication in distributed file systems G06F16/10; replication in distributed file systems G06F16/27; replication or mirroring of data in data networks H04L67/1095

Abstract

In order to reduce the amount of consumption of a back-end bandwidth in a storage apparatus, a computer system includes: a first storage device; and a second storage device that is coupled to the first controller through a first interface and is coupled to the second controller through a second interface. The first controller receives data from a host computer through a first communication channel; write the received data into the first storage device; identify part of the received data as first data, the part satisfying a preset particular condition; and write a replica of the first data as second data into the second storage device. The second controller reads the second data from the second storage device in response to a Read request received from the host computer through a second communication channel; and transmit the second data to the host computer through the second communication channel.

Claims

1. A computer system comprising:

a first controller coupled to a host computer through a first communication channel;

a second controller coupled to the host computer through a second communication channel;

a first storage device coupled to the first controller; and

a second storage device that is coupled to the first controller through a first interface and is coupled to the second controller through a second interface,

wherein the first controller is configured to;

receive data from the host computer through the first communication channel;

write the received data into the first storage device;

identify part of the received data as first data, the part satisfying a preset particular condition; and

write a replica of the first data as second data into the second storage device, and

wherein the second controller is configured to;

read the second data from the second storage device in response to a Read request received from the host computer through the second communication channel;

and transmit the read second data to the host computer through the second communication channel.

2. A computer system according to claim 1,

wherein the first controller is configured to write the first data into the first storage device according to a RAID scheme with redundancy;

and

write the second data into the second storage device according to a scheme with redundancy lower than that of the RAID scheme.

3. A computer system according to claim 1,

wherein the second controller is configured to transmit, in accordance with a change in a state of the second data stored in the second storage device, a state change report indicating the change, to the host computer through the second communication channel without depending on an instruction from the host computer.

4. A computer system according to claim 1,

wherein the first controller is configured to migrate the first data to a third storage device whose costs per unit storage capacity are lower than those of the first storage device, after writing the second data into the second storage device.

5. A computer system according to claim 1, further comprising the host computer,

wherein the first controller is configured to create metadata indicating an association between a storage position of the second data in the second storage device and a virtual address of the second data,

wherein the second controller is configured to transmit the metadata to the host computer through the second communication channel, and

wherein the host computer is configured to:

receive the metadata;

determine, if the Read request occurs, whether or not a virtual address designated in the Read request is included in the metadata; and

transmit, if determining that the designated virtual address is included in the metadata, the Read request to the second controller through the second communication channel.

6. A computer system according to claim 5,

wherein the host computer is configured to transmit, if determining that the designated virtual address is not included in the metadata, the Read request to the first controller through the first communication channel.

7. A computer system according to claim 6,

wherein the first controller is configured to update the metadata after writing the second data and report the update of the metadata to the second controller, and

wherein the second controller is configured to transmit the metadata to the host computer through the second communication channel.

8. A computer system according to claim 1,

wherein the particular condition requires that the first data is sequential access data.

9. A computer system according to claim 8,

wherein the particular condition requires that an access frequency of the first data satisfies a preset replication condition.

10. A computer system according to claim 9,

wherein the first controller is configured to release, if an access frequency of the second data through the second communication channel satisfies a preset release condition, a storage area of the second data.

11. A computer system according to claim 10,

wherein the first controller is configured to determine the release condition and the replication condition on a regular schedule.

12. A computer system according to claim 11,

wherein the first storage device is a hierarchical storage including a plurality of types of memory apparatuses, and

wherein the first controller is configured to migrate the first data to a layer lower than a layer in which the first data is stored, after writing the second data.

13. A computer system according to claim 5, further comprising a second host computer having a configuration of the host computer,

wherein the metadata indicates an association between a particular area in the second storage device and a virtual address of the particular area,

wherein the host computer is configured to transmit second written data to the second controller through the second communication channel, on a basis of the metadata, and

wherein the second controller is configured to:

receive the second written data;

write the second written data into the particular area;

create metadata indicating an association between a storage position of the second written data and a virtual address of the second written data;

and transmit the created metadata to the host computer and the second host computer through the second communication channel.

14. A computer system according to claim 1, further comprising a storage apparatus coupled to the second controller through the second communication channel,

wherein the first controller is configured to:

write difference data indicating update of data in the first storage device during a particular period, into the second storage device; and

create metadata for difference indicating an association between a storage position of the difference data in the second storage device and a virtual address of the difference data,

wherein the second controller is configured to transmit the metadata for difference to the storage apparatus through the second communication channel,

wherein the storage apparatus is configured to;

receive the metadata for difference; and

transmit a Read request of the difference data to the second controller through the second communication channel, on a basis of the metadata for difference, and

wherein the second controller is configured to;

read, if receiving the Read request of the difference data from the storage apparatus through the second communication channel, the difference data from the second storage device; and

transmit the read difference data to the storage apparatus through the second communication channel.

15. A method of controlling a computer system, comprising:

receiving, by a first controller coupled to a host computer through a first communication channel, data from the host computer through the first communication channel;

writing, by the first controller, the received data into a first storage device coupled to the first controller;

identifying, by the first controller, part of the received data as first data, the part satisfying a preset particular condition;

writing, by the first controller, second data that is a replica of the first data, into a second storage device through a first interface; and

reading, by a second controller coupled to the host computer through a second communication channel, the second data from the second storage device through a second interface in response to a Read request received from the host computer through the second communication channel, and transmitting the second data to the host computer through the second communication channel.