Computer system and data access control method for recalling the stubbed file on snapshot

• US 8,538,924 B2
• Filed: 08/31/2011
• Issued: 09/17/2013
• Est. Priority Date: 08/31/2011
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Saika, Nobuyuki
• Primary Examiner(s): Mahmoudi, Tony
• Assistant Examiner(s): Le, Michael
• Application Number:
  US13/257,905
• Publication Number:
  US 20130054528A1
• Time in Patent Office: 748 Days
• Field of Search: 707/638
• US Class Current: 707/638
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0637 Permissions
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]

Abstract

Proposed is a convenient computer system and data access control method which, while protecting data in a snapshot, enable restoration in operational volume file units.

If a read request to read a stubbed file in the snapshot is supplied, the data of the file is acquired from a second logical volume of an archive destination by means of recall processing and the acquired data is transmitted to the source of the read request after writing the acquired data to the snapshot, but, if a write request to write to a file in the snapshot is supplied, the write request is rejected.

Claims

1. A computer system, comprising:

a first storage apparatus configured to provide a first storage area for reading and writing data;

a file storage apparatus configured to read or write data in file units to a first logical volume which is defined in the first storage area of the first storage apparatus in response to a request from a client or a host;

a second storage apparatus configured to provide a second storage area for reading and writing data; and

an archive apparatus configured to read or write data in file units to a second logical volume which is defined in the second storage area of the second storage apparatus in response to a request from the file storage apparatus,

wherein the file storage apparatus is configured to;

send and receive data to and from the archive apparatus;

construct a file system in the first logical volume and manage the data stored in the first logical volume;

acquire a snapshot which is a static image of the first logical volume;

transfer, when necessary, data of files stored in the first logical volume to the archive apparatus and creates replication of the files in the second logical volume of the second storage apparatus, while monitoring the residual capacity of the file system constructed in the first logical volume

if the residual capacity should fall below a predetermined value, issue a request to stub the required number of files from among the files for which the replication was created and issue a request to acquire a snapshot of the first logical volume after the file is stubbed,

stub the designated files,

acquire a snapshot of the first logical volume,

when receiving a file access request to the snapshot,

if a target file of the file access request is the stubbed file and the file access request is a write request, reject the write request,

if a target file of the file access request is not the stubbed file and the file access request is a read request, execute a processing of the read request,

if a target file of the file access request is not the stubbed file and the file request is a write request, reject the write request, and

if a target file of the file access request is the stubbed file and the file request is a read request, recall the target file from the archive apparatus when necessary, reserve a storage area on the snapshot, store the recalled target file in the storage area on the snapshot and execute a processing of the read request.

2. The computer system according to claim 1,

wherein the file storage apparatus is further configured to:

manage version information indicating the number of file updates for each of the files which are management targets, and,

at the time of the recall processing, issue a recall request designating version information on the files which are recall targets, and

acquire the data of the recall target files from the second logical volume in the second storage apparatus via the archive apparatus on the basis of the version information, and supply this file data.

3. The computer system according to claim 1,

wherein, when the data is initially written to each area in the first logical volume after acquiring a snapshot of the first logical volume, the file storage apparatus is further configured to save the data immediately before the data is written, in a third logical volume which is defined in the first storage area of the first storage apparatus, and

at the time of the recall processing for acquiring the data of the stubbed file in the snapshot, store the data acquired from the second logical volume of the second storage apparatus in the third logical volume.

4. A data access control method for a computer system which comprises a first storage apparatus configured to provide a first storage area for reading and writing data, a file storage apparatus configured to read or write data in file units to a first logical volume which is defined in the first storage area of the first storage apparatus in response to a request from a client or a host,

a second storage apparatus configured to provide a second storage area for reading and writing data, and an archive apparatus configured to read or write data in file units to a second logical volume which is defined in the second storage area of the second storage apparatus in response to a request from the file storage apparatus,

the data access control method comprising the steps of:

sending and receiving data between the archive apparatus and the file storage apparatus;

constructing a file system in the first logical volume and managing the data stored in the first logical volume;

transferring, when necessary, data of files stored in the first logical volume to the archive apparatus and creating replication of the files in the second logical volume of the second storage apparatus;

monitoring the residual capacity of the file system constructed in the first logical volume and, if the residual capacity should fall below a predetermined value, issuing a request to stub the required number of files from among the files for which the replication was created and issuing a request to acquire a snapshot of the first logical volume after the file is stubbed;

stubbing the designated files;

acquiring a snapshot of the first logical volume;

when receiving a file access request to the snapshot,

if a target file of the file access request is the stubbed file and the file access request is a write request, rejecting the write request,

if a target file of the file access request is not the stubbed file and the file access request is a read request, executing a processing of the read request,

if a target file of the file access request is not the stubbed file and the file request is a write request, rejecting the write request, and

if a target file of the file access request is the stubbed file and the file request is a read request, recalling the target file from the archive apparatus to the file storage apparatus when necessary, reserving a storage area on the snapshot, storing the recalled target file in the storage area on the snapshot and executing a processing of the read request.

5. The data access control method according to claim 4, further comprising the steps of:

managing version information indicating the number of file updates for each of the files which are management targets,

at the time of the recall processing issuing a recall request designating version information on the files which are recall targets, and

acquiring the data of the recall target files from the second logical volume in the second storage apparatus via the archive apparatus on the basis of the version information, and supplying this file data.

6. The data access control method according to claim 4, further comprising the steps of:

when the data is initially written to each area in the first logical volume after acquiring a snapshot of the first logical volume, saving the data immediately before the data is written, in a third logical volume which is defined in the first storage area of the first storage apparatus, and

at the time of the recall processing for acquiring the data of the stubbed file in the snapshot, storing the data acquired from the second logical volume of the second storage apparatus in the third logical volume.