# US 2014/0195722 A1 · Storage system which realizes asynchronous remote copy using cache memory composed of flash memory, and control method thereof

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- Number: US 2014/0195722 A1
- Document ID: US20140195722A1
- Status: Published application
- Kind: A1
- Application number: 13/816,834
- Filed: 2013-01-07
- Published: 2014-07-10
- Earliest claimed: 2013-01-07
- Assignees: Hitachi, Ltd.
- Inventors: Kohei Tatara; Akira Yamamoto; Junji Ogawa
- Web page: https://patentgrep.com/patent/US20140195722A1

## CPC

- G06F 12/0246: {in block erasable memory, e.g. flash memory}
- G06F 3/061: {Improving I/O performance}
- G06F 3/065: {Replication mechanisms}
- G06F 3/067: {Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]}
- G06F 11/2074: {Asynchronous techniques}
- G06F 12/0806: Multiuser, multiprocessor or multiprocessing cache systems
- G06F 2201/855: Details of asynchronous mirroring using a journal to transfer not-yet-mirrored changes
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

The first storage apparatus provides a primary logical volume, and the second storage apparatus has a secondary logical volume. When the first storage apparatus receives a write command to the primary logical volume, a package processor in a flash package allocates first physical area in the flash memory chip to first cache logical area for write data and stores the write data to the allocated first physical area. And when the package processor receives journal data creation command form the processor, allocates the first physical area to second journal area for journal data without storing journal data corresponding to the write data.

## Claims

### Claim 1

A storage system comprising:
a first storage apparatus including a first processor, a first memory device providing storage area for a primary logical volume, and a first flash package which has a plurality of first flash memory chips and a first package processor and temporarily stores data to be wrote to the primary logical volume; and
a second storage apparatus including a second processor, and a second memory device providing storage are for a secondary logical volume, and receiving journal data corresponding to write data to the primary logical volume and update information, and reflecting the journal data to the secondary logical volume according to the update information;
wherein when the first storage apparatus receives a write command which requests to write a first write data to the primary volume,
the first package processor in the flash package receives the first write data transferred by control of the first processor, allocates first physical area in the first flash memory chips to first cache logical area for write data managed by the first flash package, and writes the first write data to the allocated first physical area,
the first package processor in the flash package receives first journal data creation request corresponding to the first write data from the first processor, and allocates the first physical area which stores the first write data to second cache logical area for journal data managed by the first flash package.

### Claim 2 (depends on 1)

A storage system according to claim 1,
wherein the first processor sends the first journal data creation request, which includes information of the first cache logical area and information of the second cache logical area, to the first flash package, and
wherein the first package processor allocates the first physical area, which is allocated to the first cache logical area, to the second cache logical area by referring the information of the first cache logical area and the information of the second cache logical area included in the first journal data creation request.

### Claim 3 (depends on 2)

A storage system according to claim 2,
wherein the first package processor sends a completion report to the first journal data creation request after allocating the first physical area to the second cache logical area for journal data, and
wherein the first processor sends write completion notification to the write command after detecting completion of storing the first write data to the first flash package and receiving the completion report from the first flash package.

### Claim 4 (depends on 3)

A storage system according to claim 3,
wherein the first processor creates first update information, which includes a first sequential number indicating write order of the first write data, and sends the first update information to the first flash package, and
wherein the first package processor allocates second physical area in the first flash memory chips to third cache logical area for update information managed by the first flash package, and stores the first update information to the allocated second physical area.

### Claim 5 (depends on 4)

A storage system according to claim 4,
wherein when the first storage apparatus receives a read journal command from the second storage apparatus, and
the first processor reads the first update information and the first journal data from the first flash package according to the first sequential number included in the read journal command, and sends the first update information and the first journal data to the second storage apparatus.

### Claim 6 (depends on 5)

A storage system according to claim 5,
wherein a second storage apparatus further including a second flash package which has a plurality of second flash memory chips and second package processor and temporarily stores data to be wrote to the secondary logical volume,
wherein the second package processor in the second flash package allocates first physical area, which stores the first journal data, in the second flash memory chips to the second cache logical area for journal data managed by the second flash package, and
wherein when the second package processor in the second flash package reflects the first journal data to the secondary logical volume, the second package processor allocates the first physical area of the second flash memory chips to first cache logical area for write data managed by the second flash package.

### Claim 7 (depends on 6)

A storage system according to claim 6,
wherein the second processor destages the first journal data stored in the first physical area, which is allocated to the first cache logical area for write data, to the secondary logical volume.

### Claim 8 (depends on 7)

A storage system according to claim 7,
wherein the first storage apparatus manages a primary journal logical volume provided by the plurality of first memory devices,
wherein the first package processor releases allocation of the first physical area to the first cache logical area, after the first processor destages the first write data from the first cache logical area to the primary logical volume or after the first package processor writes updated data to the first cache logical area,
wherein the first package processor releases allocation of the first physical area to the second cache logical area, after the first processor destages the first journal data from the second cache logical area to the primary journal logical volume, and
wherein the first package processor manages the first physical area, from which allocation to the first cache logical area and the second cache logical area is released, as physical area to be reclaimed.

### Claim 9 (depends on 7)

A storage system according to claim 7,
wherein the first package processor releases allocation of the first physical area to the first cache logical area, after the first processor destages the first write data from the first cache logical area to the primary logical volume or after the first package processor writes updated data to the first cache logical area,
wherein the first package processor releases allocation of the first physical area to the second cache logical area, after receiving the first sequential number of the first journal data which is reflected on the secondary logical volume from the second storage apparatus, and
wherein the first package processor manages the first physical area, from which allocation to the first cache logical area and the second cache logical area is released, as physical area to be reclaimed.

### Claim 10

A control method for a storage apparatus including a processor, a plurality of memory devices, and cache package having a plurality of flash memory chips and a package processor, the control method comprising:
providing a primary logical volume provided by the plurality of memory devices;
receiving a write command which requests to write a write data to the primary logical volume;
allocating, by the package processor, first physical area in the flash memory chips to first cache logical area for write data managed by the cache package, and storing the write data to the allocated first physical area;
sending, by the processor, a creation command of journal data corresponding to the write data to the cache package;
allocating, by the package processor, the first physical area, in which the write data is stored, to second cache logical area for journal data managed by the cache package; and
sending the journal data to another storage apparatus.