Reclamation of storage medium

Patent metadata

Field	Value
Publication number	US-10042556-B2
Application number	US-201514813191-A
Country	US
Kind code	B2
Filing date	Jul 30, 2015
Priority date	Jul 30, 2015
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

Software for reclaiming a storage medium. The software receives a read request targeting data in a storage system. The software reads the targeted data from a first storage medium storing the targeted data. The software responds to the read request with the targeted data. Responsive to reading the targeted data from the first storage medium and responsive to determining that the first storage medium meets a predetermined condition, the software writes the targeted data to a second storage medium for reclamation. The software may also, subsequent to writing the targeted data to the second storage medium for reclamation, explicitly reclaim the data on the first storage medium to the second storage medium, wherein a time required for explicitly reclaiming is reduced due to the targeted data having already been written to the second storage medium.

First claim

What is claimed is:

1. A method for reclaiming a storage medium, the method comprising:
receiving, by one or more processors, a read request targeting data in a storage system, wherein the storage system includes sequential access tape media that store files in a linear tape file system (LTFS) format;
reading, by one or more processors, the targeted data from a first storage medium storing the targeted data in the LTFS format;
responding, by one or more processors, to the read request with the targeted data;
determining, by one or more processors, that the first storage medium meets a predetermined condition indicating that the first storage medium should be reclaimed, wherein the predetermined condition is a policy based on a generation of the first storage medium and on a utilization of the first storage medium, and wherein the predetermined condition is met when the generation of the first storage medium is older than a first predetermined threshold and when a percentage of valid capacity for valid files to a total tape capacity of the first storage medium is below a second predetermined threshold;
responsive to reading the targeted data from the first storage medium, and responsive to determining that the first storage medium meets the predetermined condition, writing, by one or more processors, the targeted data to a second storage medium in the LTFS format, wherein the second storage medium is selected based on a generation of the second storage medium, wherein the generation of the second storage medium is newer than the generation of the first storage medium;
subsequent to writing the targeted data to the second storage medium, reconciling, by one or more processors, the first storage medium to delete expired data; and
subsequent to reconciling the first storage medium, explicitly reclaiming, by one or more processors, data on the first storage medium to the second storage medium in the LTFS format, wherein a time required for explicitly reclaiming is reduced due to the targeted data having already been written to the second storage medium, and due to the deleted expired data not having to be written to the second storage medium.

2. The method of claim 1 , further comprising:
responsive to writing the targeted data, updating, by one or more processors, metadata for the targeted data to indicate that the targeted data is stored on the second storage medium.

3. The method of claim 1 , wherein the storage system is a hierarchical storage system that includes a tape tier having the first storage medium and the second storage medium, and one or more upper tiers above the tape tier in the hierarchical storage system.

4. The method of claim 3 , further comprising:
responsive to reading the targeted data from the first storage medium, storing, by one or more processors, the targeted data on at least one upper tier.

5. The method of claim 1 , wherein the selection of the second storage medium is further based on timing of the read request, frequency of access to the targeted data, or frequency distribution of timing of access to the targeted data.

6. The method of claim 1 , further comprising:
migrating, by one or more processors, at least one of newly created data or overwritten data in the storage system to a storage medium other than the first storage medium.

7. The method of claim 1 , wherein reconciling the first storage medium to delete expired data includes:
identifying retention periods for digital documents stored on the first storage medium, wherein the retention periods are adapted to meet legal data archival requirements; and
responsive to determining that a first digital document's respective retention period has expired, deleting the first digital document.

8. The method of claim 7 , wherein the first digital document's respective retention period expires when the first digital document is not read, overwritten, or created within a given time period.

9. A computer program product for reclaiming a storage medium, the computer program product comprising a computer readable storage medium having stored thereon:
program instructions programmed to receive a read request targeting data in a storage system, wherein the storage system includes sequential access tape media that store files in a linear tape file system (LTFS) format;
program instructions programmed to read the targeted data from a first storage medium storing the targeted data in the LTFS format;
program instructions programmed to respond to the read request with the targeted data;
program instructions programmed to determine that the first storage medium meets a predetermined condition indicating that the first storage medium should be reclaimed, wherein the predetermined condition is a policy based on a generation of the first storage medium and on a utilization of the first storage medium, and wherein the predetermined condition is met when the generation of the first storage medium is older than a first predetermined threshold and when a percentage of valid capacity for valid files to a total tape capacity of the first storage medium is below a second predetermined threshold;
responsive to reading the targeted data from the first storage medium, and responsive to determining that the first storage medium meets the predetermined condition, write the targeted data to a second storage medium in the LTFS format, wherein the second storage medium is selected based on a generation of the second storage medium, wherein the generation of the second storage medium is newer than the generation of the first storage medium;
program instructions programmed to, subsequent to writing the targeted data to the second storage medium, reconcile the first storage medium to delete expired data; and
program instructions programmed to, subsequent to reconciling the first storage medium, explicitly reclaim data on the first storage medium to the second storage medium in the LTFS format, wherein a time required for explicitly reclaiming is reduced due to the targeted data having already been written to the second storage medium, and due to the deleted expired data not having to be written to the second storage medium.

10. The computer program product of claim 9 , further comprising:
program instructions programmed to, responsive to writing the targeted data, update metadata for the targeted data to indicate that the targeted data is stored on the second storage medium.

11. The computer program product of claim 9 , further comprising:
program instructions programmed to, responsive to reading the targeted data from the first storage medium, store the targeted data on at least one upper tier of the storage system, wherein the at least one upper tier of the storage system is above a tape tier having the first storage medium and the second storage medium.

12. The computer program product of claim 9 , wherein the selection of the second storage medium is further based on timing of the read request, frequency of access to the targeted data, or frequency distribution of timing of access to the targeted data.

13. The computer program product of claim 9 , wherein the program instructions programmed to reconcile the first storage medium to delete expired data include:
program instructions programmed to identify retention periods for digital documents stored on the first storage medium, wherein the retention periods are adapted to meet legal data archival requirements; and
program instructions programmed to, responsive to determining that a first digital document's respective retention period has expired, delete the first digital document.

14. The computer program product of c

Assignees

• IBM

Inventors

• Hasegawa Tohru
• Iwanaga Masayuki
• Oishi Yutaka

Classifications

• G06F3/0686

  Libraries, e.g. tape libraries, jukebox · CPC title

• G06F3/0608 Primary

  Saving storage space on storage systems · CPC title

• G06F3/065

  Replication mechanisms · CPC title