Storage system including multiple storage apparatuses and pool virtualization method

Patent metadata

Field	Value
Publication number	US-9104590-B2
Application number	US-201213639931-A
Country	US
Kind code	B2
Filing date	Jul 20, 2012
Priority date	Jul 20, 2012
Publication date	Aug 11, 2015
Grant date	Aug 11, 2015

Abstract

A plurality of storage apparatuses including a first and second storage apparatus, wherein said first storage apparatus is configured to have a first virtual volume composed of a plurality of virtual segments, at least said second storage apparatus is configured to have a pool composed of a plurality of real pages, each storage apparatuses is configured to manage a virtual pool comprising one or more pools including at least said pool, said virtual pool is composed of a plurality of virtual pages, each virtual page corresponding to any real page, and said first storage apparatus is configured to receive a write command that specifies an address belonging to an unallocated virtual segment, allocate a free virtual page to said unallocated virtual segment, and write data to the real page corresponding to the allocated virtual page, even when said first storage apparatus does not have a pool composed of real pages.

First claim

The invention claimed is:

1. A storage system, comprising:
a plurality of storage apparatuses including a first storage apparatus and a second storage apparatus, wherein:
said first storage apparatus is configured to have a first virtual volume composed of a plurality of virtual segments,
at least said second storage apparatus is configured to have a pool,
each storage apparatus of said plurality of storage apparatuses is configured to manage a virtual pool regardless of whether the each storage apparatus has a pool itself, said virtual pool being obtained by virtualizing a plurality of pools,
wherein said plurality of pools include at least said pool in said second storage apparatus and each of the plurality of pools is composed of a plurality of real pages, and
wherein said virtual pool is composed of a plurality of virtual pages, each virtual page of the virtual pool corresponding to any of the real pages in the plurality of pools, and

said first storage apparatus is configured to:
receive, from a host computer, a write command that specifies an address belonging to an unallocated virtual segment in the first virtual volume to which no virtual page in the virtual pool is allocated,
allocate a free virtual page from said virtual pool to said unallocated virtual segment in the first virtual volume, and
write data accompanying said write command to a corresponding real page among the plurality of real pages in the plurality of pools, the corresponding real page corresponding to the allocated virtual page, even when said first storage apparatus does not have a pool composed of a plurality of real pages,
wherein at least one of said plurality of storage apparatuses comprises a free queue that is a queue with one or more free virtual pages,
wherein said first storage apparatus, when the free virtual page to be allocated to the unallocated virtual segment is a first virtual page corresponding to a real page in the pool provided in said second storage apparatus, is configured to send an inquiry relating to the first virtual page to said storage apparatus with the free queue,
wherein said storage apparatus with the free queue is configured to receive the inquiry, secure the first virtual page from the free queue to set the first virtual page to an allocated status in response to said inquiry, and transmit a reply indicating that the first virtual page has been allocated to said first storage apparatus,
wherein said first storage apparatus is configured to receive the reply and allocate the first virtual page to the unallocated virtual segment,
wherein said storage apparatus with the free queue, when the first virtual page has been allocated, is configured to secure, from the free queue, a second virtual page which is a free virtual page different from the first virtual page and which corresponds to a real page in the pool provided in said second storage apparatus, to set the second virtual page to an allocated status, and to transmit a reply indicating that the second virtual page has been allocated to said first storage apparatus, and
wherein said first storage apparatus is configured to receive the reply and allocate the second virtual page to the unallocated virtual segment.

2. The storage system according to claim 1 ,
wherein said first storage apparatus is configured to store mapping information that is information that indicates which virtual page is allocated to which virtual segment,
wherein said first storage apparatus is configured to migrate said first virtual volume to a third storage apparatus that is one of said plurality of storage apparatuses other than said first storage apparatus and transmit said mapping information corresponding to said first virtual storage apparatus to said third storage apparatus,
wherein said third storage apparatus is said second storage apparatus or another storage apparatus,
wherein said third storage apparatus receives said first virtual volume and said mapping information, and
wherein said third storage apparatus is configured to receive a read command that specifies an address belonging to a virtual segment in said first virtual volume, determine a virtual page allocated to the virtual segment from said mapping information, and read data from the real page corresponding to the determined virtual page.

3. The storage system according to claim 2 ,
wherein said virtual pool is composed of a plurality of tiers,
wherein each tier is composed of two or more virtual pages of a same virtual page type,
wherein the virtual page type of the virtual page is defined according to what physical storage device in which storage apparatus the real page associated with the virtual page relies on, and
wherein the correlation between the virtual page types and the tiers differs among the storage apparatuses.

4. The storage system according to claim 3 ,
wherein each storage apparatus is configured to store tier information that indicates what virtual page type corresponds to which tier, and
wherein the migration of said first virtual volume and a volume migration process is configured to be performed, the volume migration process including:
(a) said first or third storage apparatus determining the virtual page type of a destination of data in said third storage apparatus for each of one or more virtual pages allocated to said first virtual volume based on said mapping information, the tier information in said first storage apparatus and the tier information in said third storage apparatus;
(b) said first or third storage apparatus determining whether or not, of the one or more virtual pages allocated to said first virtual volume, there is a virtual page that belongs to a virtual page type different from the virtual page type determined in said (a);
(c) when there is a virtual page that belongs to a virtual page type different from the virtual page type determined in said (a), said first or third storage apparatus migrating data from the virtual page to a virtual page that belongs to the virtual page type determined in said (a); and
(d) said third storage apparatus updating said mapping information so that instead of the virtual page that is the source of the migration in said (c), the virtual page that is the destination of the migration in said (c) is allocated to the virtual segment to which the virtual page that is the source of the migration in said (c) is allocated.

5. The storage system according to claim 4 ,
wherein in said (c), said first or third storage apparatus is configured to perform the data migration when an access frequency of data in the virtual page that belongs to the virtual page type different from the virtual page type determined in said (a) is equal to or larger than a predetermined value and skip the data migration when the access frequency of the data in the virtual page that belongs to the virtual page type different from the virtual page type determined in said (a) is less than the predetermined value, and
wherein the data migration skipped in said volume migration process is configured to be performed at a time after said volume migration process.

6. The storage system according to claim 4 ,
wherein an external storage apparatus different from said plurality of storage apparatuses is coupled to said first storage apparatus,
wherein in said (c), said first or third storage apparatus is configured to perform the data migration when data in the virtual page that belongs to the virtual page type different from the virtual page type determined in said (a) exists in said first storage apparatus and skip the data migration when the data in the virtual page that belongs to the virtual page type different from the virtual page type determined in said (a) exists in said external storage apparatus, and
wherein the dat

Assignees

• Satoyama Ai
• Eguchi Yoshiaki
• Hitachi Ltd

Inventors

• Satoyama Ai
• Eguchi Yoshiaki

Classifications

• G06F3/0607 Primary

  by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device · CPC title

• G06F3/0683

  Plurality of storage devices · CPC title

• G06F12/1009 Primary

  using page tables, e.g. page table structures · CPC title

• G06F3/0665

  at area level, e.g. provisioning of virtual or logical volumes · CPC title

• G06F3/0689

  Disk arrays, e.g. RAID, JBOD · CPC title