Automated reclamation scheduling override in a virtual tape server

• US 6,304,880 B1
• Filed: 12/12/1997
• Issued: 10/16/2001
• Est. Priority Date: 12/12/1997
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kishi, Gregory Tad
• Primary Examiner(s): Alam, Hosain T.
• Assistant Examiner(s): FLEURANTIN, JEAN B
• Application Number:
  US08/989,501
• Time in Patent Office: 1,404 Days
• Field of Search: 707/200, 707/206, 707/205, 707/100-101, 711/114
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0686 Libraries, e.g. tape libraries, jukebox
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

An automated reclamation scheduling system and method are taught for managing storage reclamation on a virtual tape server. Where reclamation-off times are set by a user, an automated administrator may override the settings depending on the number of scratch tapes that are available. The fewer scratch tapes that remain available, the more frequently storage reclamation will be performed in the reclamation schedule set by the automated administrator.

Claims

1. A method for managing storage reclamation on a virtual tape server having a plurality of tape devices, a library manager, and a number of scratch tapes, comprising the steps of:

receiving reclamation-off times from the library manager, wherein the reclamation-off times identify periods in which reclamation processing is prohibited;

determining a number of scratch tapes; and

setting a reclamation schedule identifying periods in which reclamation processing is permitted and prohibited, wherein the reclamation schedule is a function of the number of scratch tapes that are available and the reclamation-off times.

2. The method of claim 1, wherein the reclamation schedule includes a reclamation frequency, the reclamation frequency being inversely related to the number of scratch tapes.

3. The method of claim 1, wherein setting the reclamation schedule further comprises the steps of:

overriding the reclamation off-times to perform frequent reclamation, when the number of tapes is below a first threshold;

performing reclamation according to reclamation-off times, when the number of tapes is at or above the first threshold and below a second threshold; and

performing reclamation according to reclamation-off times when the VTS is not occupied, when the number of tapes is at or above the second threshold.

4. The method of claim 3, wherein the first threshold is ten.

5. The method of claim 3, wherein the second threshold is fifty.

6. The method of claim 3, wherein the virtual tape server is not occupied when two drives are free for a first predetermined time period or three drives are free for a second predetermined time period.

7. The method of claim 6, wherein the first predetermined time period is equal to the second predetermined time period.

8. The method of claim 6, wherein the first predetermined time period is greater than the second predetermined time period.

9. The method of claim 6, wherein the first predetermined time period is 30 minutes and the second predetermined time period is 20 minutes.

10. A storage reclamation management method on a virtual tape server having a plurality of tape devices, a library manager, and a number of scratch tapes, comprising the steps of:

receiving reclamation-off times from the library manager;

determining a number of scratch tapes;

overriding the reclamation off-times to perform frequent reclamation, when the number of tapes is below a first threshold;

performing reclamation according to reclamation-off times, when the number of tapes is at or above the first threshold and below a second threshold; and

performing reclamation according to reclamation-off times when the VTS is not occupied, when the number of tapes is at or above the second threshold.

11. A storage reclamation management system on a virtual tape server having a number of scratch tapes, the system comprising:

a plurality of tape devices;

a library manager comprising a setting for reclamation-off times;

an administrator comprising a reclamation subsystem, where the reclamation subsystem operates on a reclamation schedule that depends on the number of scratch tapes.

12. The system of claim 11 wherein the library manager setting for reclamation-off times is entered by a customer.

13. The system of claim 11, wherein the reclamation schedule includes a reclamation frequency, the reclamation frequency being inversely related to the number of scratch tapes.

14. The system of claim 11 wherein the reclamation subsystem:

overrides the reclamation off-times to perform frequent reclamation, when the number of tapes is below a first threshold,

performs reclamation according to reclamation-off times, when the number of tapes is at or above the first threshold and below a second threshold, and

performs reclamation according to reclamation-off times when the VTS is not occupied, when the number of tapes is at or above the second threshold.

15. The system of claim 14, wherein the virtual tape server is not occupied when two drives are free for a first predetermined time period or three drives are free for a second predetermined time period.

16. The system of claim 15, wherein the first predetermined time period is equal to the second predetermined time period.

17. The system of claim 15, wherein the first predetermined time period is greater than the second predetermined time period.

18. The system of claim 15, wherein the first predetermined time period is 30 minutes and the second predetermined time period is 20 minutes.

19. An article of manufacture comprising a program storage medium readable by a computer having a memory, the medium tangibly embodying one or more programs of instructions executable by the computer to perform method steps for managing storage reclamation on a virtual tape server having a plurality of tape devices, a library manager, and a number of scratch tapes, the method comprising the steps of:

receiving reclamation-off times from the library manager, wherein the reclamation-off times identify periods in which reclamation processing is prohibited;

determining a number of scratch tapes that are available; and

setting a reclamation schedule identifying periods in which reclamation processing is permitted and prohibited, wherein the reclamation schedule is a function of the number of scratch tapes that are available and the reclamation-off times.

20. A method for performing reclamation scheduling in an external storage system, the external storage system coupled to a host processing system to provide external storage capabilities for the host processing system, the method comprising:

defining one or more predetermined reclamation-off times during which reclamation processing of the external storage system is prohibited;

performing reclamation processing of the external storage system at times other than the reclamation-off times;

overriding the predetermined reclamation-off times based on predetermined conditional criteria such that reclamation processing occurs during the predetermined reclamation-off times in response to the predetermined conditional criteria.

21. The method of claim 20, further comprising determining a number of scratch tapes available to receive new data from the host processing system, and wherein overriding the predetermined reclamation-off times based on predetermined conditional criteria comprises overriding the predetermined reclamation-off times based on the number of scratch tapes available to receive new data.

22. The method of claim 21, wherein overriding the predetermined reclamation-off times based on the number of scratch tapes available comprises overriding the predetermined reclamation-off times when the number of scratch tapes available is below a predetermined threshold indicative of an unacceptably low number of available scratch tapes.

23. The method of claim 22, wherein overriding the predetermined reclamation-off times when the number of scratch tapes available is below a predetermined threshold comprises repeatedly overriding the predetermined reclamation-off times when the number of scratch tapes available is below the predetermined threshold until the number of scratch tapes available is no longer below the predetermined threshold.

24. The method of claim 20, further comprising determining whether to perform reclamation processing of the external storage system at times other than the reclamation-off times, or whether to override the predetermined reclamation-off times, based on the predetermined conditional criteria.

25. The method of claim 24, wherein the predetermined conditional criteria comprises a number of scratch tapes available to receive new data from the host processing system.

26. The method of claim 25, wherein performing reclamation processing of the external storage system at times other than the reclamation-off times comprises performing the reclamation processing while the number of scratch tapes available to receive new data is within a first range of numbers of available scratch tapes.

27. The method of claim 25, wherein overriding the predetermined reclamation-off times comprises overriding the predetermined reclamation-off times while the number of scratch tapes available to receive new data is within a second range of numbers of available scratch tapes, thereby allowing reclamation processing during the predetermined reclamation-off times.

28. The method of claim 25, further comprising:

determining whether the number of scratch tapes available to receive new data is within a third range of numbers of available scratch tapes indicative of an acceptably ample number of available scratch tapes;

determining whether the external storage system is within a reclamation-off time;

determining whether the external storage system is being occupied at a predefined low occupation level; and

performing reclamation processing when the number of scratch tapes available to receive new data is within the third range, the reclamation processing is not within the reclamation-off time, and the external storage system is being occupied at the predefined acceptably low occupation level.