METHOD OF ALLOCATING STORAGE SPACE FROM STORAGE DEVICES WITHIN A COMPUTER SYSTEM

Abstract

A method and system for allocating storage space from storage devices within a computer system. The storage devices are grouped into respective homogeneous sets in which identical storage devices are included in the same homogeneous set. In accordance with the method and system, following receipt of an allocation request for storage space one or more stored response values are checked, the response values associated with at least one homogeneous set. The stored value or values represent the average response time of storage devices within the set. The homogenous set with the lowest average response time is selected. One or more stored allocation values are then checked that are associated with at least one storage device within the selected homogeneous set. The stored allocation value or values represent the current allocations of the associated storage device. The storage device is selected with the lowest current allocations and the storage space is allocated in the first available location on the selected device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary large computer system in which the techniques described below are implemented.

FIG. 2 is an example table showing stored response values.

FIG. 3 is a flow chart of a technique for monitoring the response time of a homogeneous set.

Claims

1. A method of selecting, from a plurality of groups of storage devices within a computer system, a group of storage devices for allocating storage space, the groups of storage devices representing respective homogeneous sets in which identical storage devices are included in the same homogeneous set, the method comprising: checking one or more stored response values associated with at least one homogeneous set, the stored value(s) representing the average response time of storage devices within the set; andselecting the homogeneous set with the lowest average response time.

2. The method of claim 1 wherein the stored response values representing respective homogeneous sets include respective homogeneous set identifiers and average response times.

3. A method of allocating storage space from storage devices within a computer system, the storage devices grouped into respective homogeneous sets in which identical storage devices are included in the same homogeneous set, the method comprising: receiving an allocation request for storage space,checking one or more stored response values associated with at least one homogeneous set, the stored value(s) representing the average response time of storage devices within the set;selecting the homogenous set with the lowest average response time;checking one or more stored allocation values associated with at least one storage device within the selected homogeneous set, the stored value(s) representing the current allocations of the associated storage device;selecting the storage device with the lowest current allocations; andallocating the storage space in the first available location on the selected device.

4. The method of claim 3 wherein the stored response values representing respective homogeneous sets include respective homogeneous set identifiers and average response times.

5. A method of monitoring the response time of a homogeneous set of identical storage devices within a computer system, the method comprising: maintaining an accumulator associated with the set;receiving a request to write to or read from a selected one of the storage devices within the homogeneous set;adding the response time of the selected device to the accumulator; andperiodically calculating a response value at least partly from the accumulator, the response value indicative of the response time of the homogeneous set.

6. The method of claim 5 further comprising the steps of: maintaining a control parameter; andrecalculating the response value once the number of requests involving a storage device within the homogeneous set, since the previous calculation of the response value, equals a threshold specified by the control parameter.

7. The method of claim 6 including the step of calculating the response value at least partly from the control parameter and the accumulator.

8. The method of claim 5 further comprising the step of calculating the response value as zero on start up of the computer system.

9. The method of claim 8 further comprising the step of calculating the response time as the response time of the selected device resulting from the first request following start up of the computer system.

10. The method of claim 5 further comprising the step of setting the accumulator to zero on start up of the computer system.

11. The method of claim 10 further comprising the step of setting the accumulator to zero after the first request following start up of the computer system.

12. A system for monitoring the response time of a homogeneous set of identical storage devices within a computer system, where the system is configured to: maintain an accumulator associated with the set;receive a request to write to or read from a selected one of the storage devices within the homogeneous set;add the response time of the selected device to the accumulator; andperiodically calculate a response value at least partly from the accumulator, the response value indicative of the response time of the homogeneous set.

13. The system of claim 12 where the system is further configured to: maintain a control parameter; andrecalculate the response value once the number of requests involving a storage device within the homogeneous set, since the previous calculation of the response value, equals a threshold specified by the controlled parameter.

14. The system of claim 13 where the system is configured to calculate the response value at least partly from the controlled parameter and the accumulator.

15. The system of claim 12 further configured to recalculate the response value as zero on start up of the computer system.

16. The system of claim 15 further configured to calculate the response time as the response time of the selected device resulting from the first request following start up of the computer system.

17. The system of claim 12 further configured to set the accumulator to zero on start up of the computer system.

18. The system of claim 17 further configured to set the accumulator to zero after the first request following start up of the computer system.

19. A computer program stored on tangible storage media comprising executable instructions for performing a method of monitoring the response time of a homogeneous set of identical storage devices within a computer system, the method comprising: maintaining an accumulator associated with the set;receiving a request to write to or read from a selected one of the storage devices within the homogeneous set;adding the response time of the selected device to the accumulator; andperiodically calculating a response value at least partly from the accumulator, the response value indicative of the response time of the homogeneous set.

20. The computer program of claim 19, the method further comprising the steps of: maintaining a control parameter; andrecalculating the response value once the number of requests involving a storage device within the homogeneous set, since the previous calculation of a response value, equals a threshold specified by the control parameter.

21. The computer program of claim 20, the method including the step of calculating the response value at least partly from the control parameter and the accumulator.

22. The computer program of claim 19, the method further comprising the step of calculating the response value as zero on start up of the computer system.

23. The computer program of claim 22, the method further comprising the step of calculating the response time as the response time of the selected device resulting from the first request following start up of the computer system.

24. The computer program of claim 19, the method further comprising the step of setting the accumulator to zero on start up of the computer system.

25. The computer program of claim 24, the method further comprising the step of setting the accumulator to zero after the first request following start up of the computer system.