Storage apparatus, storage system, and control method of storage system for dynamically securing free space when a storage apparatus is disused

Patent metadata

Field	Value
Publication number	US-10725878-B2
Application number	US-201515749014-A
Country	US
Kind code	B2
Filing date	Jul 31, 2015
Priority date	Jul 31, 2015
Publication date	Jul 28, 2020
Grant date	Jul 28, 2020

Abstract

A storage system capable of dynamically securing free space when a certain storage apparatus is disused and reducing the influence on the system upon dynamically securing the free space without having to continuously secure, in a memory of another storage apparatus, free space capable of storing management information of the corresponding storage apparatus in preparation of a case where such storage apparatus is disused. Each storage apparatus comprises a memory including a management information storage area for storing management information and a cache area for storing cache information, and a processor which manages a status of the cache area. At least certain processors determine a storage apparatus to become a copy destination of the copy target management information. The storage apparatus of the copy destination releases at least a part of the cache area and stores the management information in the released cache area.

First claim

The invention claimed is:

1. A storage system comprising a plurality of storage apparatuses including a first storage apparatus,
wherein each of the plurality of storage apparatuses comprises a memory which includes a management information storage area for storing management information and a cache area for storing cache information, and a processor which manages a status of the cache area,
wherein, when a memory of the first storage apparatus is to be disused, at least certain processors of the plurality of storage apparatuses determine a copy destination storage apparatus to become a copy destination of a copy target management information, the copy target management information is the management information stored in the memory to be disused, the copy destination storage apparatus is based on the status of the cache area that is managed by each processor other than the processor in the first storage apparatus,
wherein the copy destination storage apparatus is one of the plurality of storage apparatuses, and
wherein the processor of the copy destination storage apparatus releases at least a part of the cache area of the memory of the copy destination storage apparatus, and stored the copy target management information in the released at least part of the cache area.

2. The storage system according to claim 1 ,
wherein the management information is information which is stored in at least one of the memories of the plurality of storage apparatuses and which can be referenced by at least one of the processors of the plurality of storage apparatuses from the memory when the plurality of storage apparatuses are operating,
wherein the cache information is information which can be deleted from any one of the memories of the plurality of storage apparatuses when the information is stored in a storage device equipped in at least one of the plurality of storage apparatuses,
wherein the status of the cache area includes at least information of an access frequency of the cache area, and
wherein the plurality of copy destination candidate storage apparatuses are the plurality of storage apparatuses,
the processors of the plurality of copy destination candidate storage apparatuses:
predict a deterioration in access performance when copy target management information is copied to each of the plurality of copy destination candidate storage apparatuses based on the access frequency of the cache area managed by each of the copy destination candidate storage apparatuses; and
determine, as the copy destination storage apparatus, a storage apparatus in which a predicted deterioration in access performance is low among the plurality of copy destination candidate storage apparatuses.

3. The storage system according to claim 2 ,
wherein the plurality of storage apparatuses comprise at least the first storage apparatus, a second storage apparatus, and the copy destination storage apparatus,
wherein the copy target management information is made redundant by storing the copy target management information in a memory of the first storage apparatus and a memory of the second storage apparatus, respectively,
wherein, when the memory of the first storage apparatus is to be disused, the copy target management information is stored in the copy destination storage apparatus so as to make redundant the copy target management information by using the memory of the second storage apparatus and the memory of the copy destination storage apparatus, and
wherein the copy destination storage apparatus sends a notification of a storage destination of the copy target management information to at least certain storage apparatuses among the plurality of storage apparatuses.

4. The storage system according to claim 3 ,
wherein the plurality of copy destination candidate storage apparatuses are at least two or more storage apparatuses other than the first storage apparatus and the second storage apparatus,
wherein each of the at least two or more copy destination candidate storage apparatuses predicts a deterioration in the access performance, and sends a predicted deterioration to the second storage apparatus,
wherein the second storage apparatus determines, as a copy destination storage apparatus, a copy destination candidate storage apparatus in which the predicted deterioration in the access performance is low based on the deterioration predicted by each of the at least two or more copy destination candidate storage apparatuses, and
wherein the copy destination storage apparatus copies the copy target management information from the second storage apparatus.

5. The storage apparatus according to claim 4 ,
wherein the management information to be stored in the memory of each of the plurality of storage apparatuses includes:
integrated management information provided in each of the plurality of storage apparatuses;
shared management information which can be referenced by other storage apparatuses; and
individual management information which is management information that is individually managed by each storage apparatus and which includes information of an access frequency of the cache area of a corresponding storage apparatus, and
wherein the copy target management information is the shared management information stored in the memory of the first storage apparatus and the memory of the second storage apparatus, respectively.

6. The storage system according to claim 5 ,
wherein the processor of the copy destination storage apparatus:
divides the cache area of the memory of the copy destination storage apparatus into a plurality of small areas, and manages an access frequency of each of the plurality of small areas; and
releases at least a part of the cache area by disusing cache information stored in a small area with a low access frequency based on the access frequency of each of the plurality of small areas.

7. The storage system according to claim 6 ,
wherein the processor of the copy destination storage apparatus rearranges the cache information of the copy destination storage apparatus based on the access frequency of the cache area so that the cache area for storing the copy target management is a continuous area.

8. The storage system according to claim 6 ,
wherein the copy destination storage apparatus further includes one or more storage devices which configure a logical volume to be provided to a host computer,
wherein the processor of the copy destination storage apparatus:
manages a cache guarantee which is set in the logical volume; and
disuses the cache information stored in a small area of the cache area of the memory of the copy destination storage apparatus when the cache guarantee is satisfied even upon releasing the small area.

9. The storage system according to claim 5 ,
wherein each of the plurality of storage apparatuses includes a plurality of memories, and
wherein each storage apparatus makes redundant the individual management information of the corresponding storage apparatus by storing the individual management information in different memories within the corresponding storage apparatus.

10. The storage system according to claim 9 ,
wherein each of the plurality of storage apparatuses comprises a plurality of controllers including a memory, and
wherein each storage apparatus makes redundant the individual management information by the corresponding storage apparatus by storing the individual management information in memories of different controllers within the corresponding storage apparatus.

11. The storage system according to claim 5 ,
wherein the memory of the first storage apparatus is disused when the first storage apparatus is subject to a failure or when

Assignees

• Hitachi Ltd

Inventors

• Nagao Takashi
• Sugimoto Sadahiro
• Kawaguchi Tomohiro
• Simozono Norio

Classifications

• G06F12/0871 Primary

  Allocation or management of cache space · CPC title

• G06F11/1666

  where the redundant component is memory or memory area · CPC title

• G06F11/1658

  Data re-synchronization of a redundant component, or initial sync of replacement, additional or spare unit · CPC title

• G06F3/0646

  Horizontal data movement in storage systems, i.e. moving data in between storage devices or systems · CPC title

• G06F2212/1024

  Latency reduction · CPC title