QOS feature knobs

• US 7,047,366 B1
• Filed: 06/17/2003
• Issued: 05/16/2006
• Est. Priority Date: 06/17/2003
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Ezra, Josef
• Primary Examiner(s): Peugh, Brian R.
• Application Number:
  US10/463,247
• Time in Patent Office: 1,064 Days
• Field of Search: 711/129, 711/135, 711/133, 711/134, 711/136, 711/141, 711/111, 711/112
• US Class Current: 711/141
• CPC Class Codes: G06F 12/0804 with main memory updating G06F12/0806 takes precedence
• CPC Class Codes: G06F 12/0868 Data transfer between cache memory and other subsystems, e.g. storage devices or host systems
• CPC Class Codes: G06F 2212/282 Partitioned cache

Abstract

Described are various quality of service (QOS) parameters that may be used in characterizing device behavior in connection with a cache. A Partition parameter indicates which portions of available cache may used with data of an associated device. A Survival parameter indicates how long data of an associate device should remain in cache after use. A Linearity parameter indicates a likelihood factor that subsequent data tracks may be used such that this parameter may be used in determining whether to prefetch data. A Flush parameter indicates how long data should remain in cache after a write pending slot is returned to cache after being written out to the actual device. The QOS parameters may be included in configuration data. The QOS parameter values may be read and/or modified.

Claims

1. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume, wherein a group of one or more parameters affecting a cache characteristic is configurable on a per logical volume level of granularity; and

selecting a value for said at least one parameter, wherein said at least one parameter includes at least one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume.

2. The method of claim 1, wherein said value is determined in accordance with at least one of:

a predetermined logical volume priority, a characteristic of data stored on the logical volume, and a usage characteristic of the data stored on the logical volume.

3. The method of claim 1, further comprising:

dynamically modifying said value.

4. The method of claim 3, wherein said value is determined in accordance with tuning performance of said logical volume in a data storage system.

5. The method of claim 1, further comprising:

examining a mode setting to determine whether to use said value in connection with performing caching and a data operation associated with said logical volume.

6. The method of claim 1, wherein said logical volume is defined as one of:

a physical device, a portion of a physical device, portions of multiple physical devices, a physical device track, a logical device, a portion of a logical device, and portions of multiple logical devices.

7. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume;

selecting a value for said at least one parameter, wherein said at least one parameter includes one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume, wherein said value is determined in accordance with at least one of;

a predetermined logical volume priority, a characteristic of data stored on the logical volume, and a usage characteristic of the data stored on the logical volume; and

dynamically modifying said value, wherein said value is determined in accordance with tuning performance of said logical volume in a data storage system; and

wherein said value is a first value, and the method further comprising;

obtaining a first value for said at least one parameter from a portion of global memory;

copying said first value to another portion of memory local to a first processor controlling data operations to said logical volume;

updating said first value to a second value in said portion of global memory;

notifying a plurality of processors including said first processor of said updating;

copying said second value to said other portion of memory local to said first processor; and

using said second value by said first processor and using said first value by another processor since updating local copies of said value associated with each of said plurality of processors is performed without synchronization.

8. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume; and

selecting a value for said at least one parameter, wherein said at least one parameter includes one of;

a partition parameter, a survival parameter, a linearity parameter and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume; and

wherein said at least one parameter includes said partition parameter, and said value is one of a predetermined number of bit patterns indicating one of;

which portions of a cache may be used by said logical volume, and which caches of a plurality of caches may be used by said logical volume, and the method further comprising;

receiving by said logical volume a request for a data operation; and

using said value in determining a new cache slot to place data associated with said data operation.

9. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume;

selecting a value for said at least one parameter, wherein said at least one parameter includes one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume; and

wherein said at least one parameter includes said survival parameter, and the method comprising;

receiving by said logical volume a request for a data operation;

determining whether data associated with said data operation is in cache; and

using said value to determine a new cache position for said data affecting how long said data remains in said cache.

10. The method of claim 9, wherein said cache uses time stamps in connection with determining said new cache position and the method further comprising:

determining a time stamp value associated with said new cache position in accordance with said value.

11. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume; and

selecting a value for said at least one parameter, wherein said at least one parameter includes one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume; and

wherein said at least one parameter includes said linearity parameter, and the method further comprising;

receiving by said logical volume a request for a data operation; and

determining, using said value, whether prefetching is to be performed for said data operation.

12. The method of claim 11, further comprising:

determining, using said value, an amount of data to be prefetched if said prefetching is to be performed.

13. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume; and

selecting a value for said at least one parameter, wherein said at least one parameter includes one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume; and

wherein said at least one parameter includes said flush parameter, and the method further comprising;

writing data included in a cache slot out to said logical volume; and

using said value to determine a new cache position for said data included in said cache slot wherein said new cache position affects how long said data remains in cache.

14. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter with said logical volume;

determining a performance characteristic of said logical volume; and

selecting a value for said at least one parameter in accordance with said performance characteristic, wherein said at least one parameter includes at least one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume, wherein said survival parameter is used in connection with determining a cache slot position for a cache slot upon the occurrence of one or more of a cache hit and a cache miss for said cache slot.

15. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter with said logical volume;

determining a performance characteristic of said logical volume; and

selecting a value for said at least one parameter in accordance with said performance characteristic, wherein said at least one parameter includes at least one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume; and

wherein said logical volume is one of a plurality of logical volumes included in a data storage system, and the performance characteristic is a priority level associated with said logical volume in accordance with others of said plurality of logical volumes.

16. The method of claim 15, further comprising:

dynamically modifying said value included in a portion of global memory; and

copying said value to a local copy of parameter values for use by a processor used in connection with data operations to said logical volume.

17. The method of claim 16, wherein said processor uses a dynamically modifiable switch value to determine whether to use said value when performing a data operation and associated data caching.

18. The method of claim 16, further comprising:

modifying said value using one of;

an user interface and an application programming interface.

19. A method for determining cache behavior associated with a logical volume comprising:

associating at least one parameter affecting a caching characteristic associated with said logical volume;

selecting a value for said at least one parameter, wherein said at least one parameter includes one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume; and

using said value to determine cache portions to be used in connection with obtaining cache slots for storing data of said logical volume in cache.

20. The method of claim 19, further comprising:

using said value to determine a cache position of data associated with said logical device after a cache hit for said data has occurred, wherein said cache position affects how long said data remains in cache.

21. The method of claim 20, further comprising:

using said value to determine whether prefetching is performed in connection with a data operation associated with said logical volume.

22. The method of claim 21, further comprising:

using said value to determine an amount of data to prefetch for said data operation.

23. The method of claim 21, further comprising:

writing data out to said logical volume; and

using said value to determine a cache position to where said data is returned, said cache position affecting how long said data remains in cache.

24. A computer readable medium comprising machine executable code stored thereon for determining cache behavior associated with a logical volume, the computer readable medium comprising:

machine executable code that associates at least one parameter affecting a caching characteristic associated with said logical volume wherein a group of one or more parameters affecting a cache characteristic is configurable on a per logical volume level of granularity; and

machine executable code that selects a value for said at least one parameter, wherein said at least one parameter includes at least one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume.

25. The computer readable medium of claim 24, wherein said value is determined in accordance with at least one of:

a predetermined logical volume priority, a characteristic of data stored on the logical volume, and a usage characteristic of the data stored on the logical volume.

26. The computer readable medium of claim 24, further comprising:

machine executable code that dynamically modifies said value.

27. The computer readable medium of claim 26, wherein said value is determined in accordance with tuning performance of said logical volume in a data storage system.

28. The computer readable medium of claim 27, wherein said value is a first value, and the computer readable medium further comprising:

machine executable code that obtains a first value for said at least one parameter from a portion of global memory;

machine executable code that copies said first value to another portion of memory local to a first processor controlling data operations to said logical volume;

machine executable code that updates said first value to a second value in said portion of global memory;

machine executable code that notifies a plurality of processors including said first processor of said updating;

machine executable code that copies said second value to said other portion of memory local to said first processor; and

machine executable code that causes said second value to be used by said first processor and said first value to be used by another processor since updating local copies of said value associated with each of said plurality of processors is performed without synchronization.

29. The computer readable medium of claim 24, further comprising:

machine executable code that examines a mode setting to determine whether to use said value in connection with performing caching and a data operation associated with said logical volume.

30. The computer readable medium of claim 24, wherein said at least one parameter includes said partition parameter, and said value is one of a predetermined number of bit patterns indicating one of:

which portions of a cache may be used by said logical volume, and which caches of a plurality of caches may be used by said logical volume, and the computer readable medium further comprising;

machine executable code that receives, by said logical volume, a request for a data operation; and

machine executable code that uses said value in determining a new cache slot to place data associated with said data operation.

31. The computer readable medium of claim 24, wherein said at least one parameter includes said survival parameter, and the computer readable medium comprising:

machine executable code that receives by said logical volume a request for a data operation;

machine executable code that determines whether data associated with said data operation is in cache; and

machine executable code that uses said value to determine a new cache position for said data affecting how long said data remains in said cache.

32. The computer readable medium of claim 31, wherein said cache uses time stamps in connection with determining said new cache position and the computer readable medium further comprising:

machine executable code that determines a time stamp value associated with said new cache position in accordance with said value.

33. The computer readable medium of claim 24, wherein said at least one parameter includes said linearity parameter, and the computer readable medium further comprising:

machine executable code that receives by said logical volume a request for a data operation; and

machine executable code that determines, using said value, whether prefetching is to be performed for said data operation.

34. The computer readable medium of claim 33, further comprising:

machine executable code that determines, using said value, an amount of data to be prefetched if said prefetching is to be performed.

35. The computer readable medium of claim 24, wherein said at least one parameter includes said flush parameter, and the computer readable medium further comprising:

machine executable code that writes data included in a cache slot out to said logical volume; and

machine executable code that uses said value to determine a new cache position for said data included in said cache slot wherein said new cache position affects how long said data remains in cache.

36. The computer readable medium of claim 24, wherein said logical volume is defined as one of:

a physical device, a portion of a physical device, portions of multiple physical devices, a physical device track, a logical device, a portion of a logical device, and portions of multiple logical devices.

37. The computer readable medium of claim 24, further comprising;

machine executable code that uses said value to determine cache portions to be used in connection with obtaining cache slots for storing data of said logical volume in cache.

38. The computer readable medium of claim 37, further comprising:

machine executable code that uses said value to determine a cache position of data associated with said logical device after a cache hit for said data has occurred, wherein said cache position affects how long said data remains in cache.

39. The computer readable medium of claim 38, further comprising:

machine executable code that uses said value to determine whether prefetching is performed in connection with a data operation associated with said logical volume.

40. The computer readable medium of claim 39, further comprising:

machine executable code that uses said value to determine an amount of data to prefetch for said data operation.

41. The computer readable medium of claim 39, further comprising:

machine executable code that writes data out to said logical volume; and

machine executable code that uses said value to determine a cache position to where said data is returned, said cache position affecting how long said data remains in cache.

42. A computer readable medium comprising machine executable code stored thereon for determining cache behavior associated with a logical volume, the computer readable medium comprising:

machine executable code that associates at least one parameter with said logical volume;

machine executable code that determines a performance characteristic of said logical volume; and

machine executable code that selects a value for said at least one parameter in accordance with said performance characteristic, wherein said at least one parameter includes at least one of;

a partition parameter, a survival parameter, a linearity parameter, and a flush parameter, said partition parameter designating which portions of cache may be used by said logical volume, said survival parameter affecting a time period that a portion of data associated with said logical volume remains in cache, said linearity parameter affecting whether data prefetching is performed for said logical volume, and said flush parameter affecting a time period a portion of data associated with said logical volume remains in cache after destaging a write of said data to said logical volume wherein said survival parameter is used in connection with determining a cache slot position for a cache slot upon the occurrence of one or more of a cache hit and a cache miss for said cache slot.

43. The computer readable medium of claim 42, wherein said logical volume is one of a plurality of logical volumes included in a data storage system, and the performance characteristic is a priority level associated with said logical volume in accordance with others of said plurality of logical volumes.

44. The computer readable medium of claim 43, further comprising:

machine executable code that that dynamically modifies said value included in a portion of global memory; and

machine executable code that copies said value to a local copy of parameter values for use by a processor used in connection with data operations to said logical volume.

45. The computer readable medium of claim 44, wherein said processor uses a dynamically modifiable switch value to determine whether to use said value when performing a data operation and associated data caching.

46. The computer readable medium of claim 44, further comprising:

machine executable code that modifies said value using one of;

an user interface and an application programming interface.