Caching data using multiple cache devices

• US 9,274,954 B1
• Filed: 12/18/2012
• Issued: 03/01/2016
• Est. Priority Date: 12/18/2012
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Bairavasundaram, Lakshmi Narayanan, Soundararajan, Gokul, Storer, Mark Walter
• Primary Examiner(s): Rutz, Jared
• Assistant Examiner(s): Wu, Stephanie
• Application Number:
  US13/718,700
• Time in Patent Office: 1,169 Days
• Field of Search: 711119-120
• US Class Current: 1/1
• CPC Class Codes: G06F 11/073 in a memory management context, e.g. virtual memory or cache management memory management G06F12/00; testing of static memory units G11C29/00
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems
• CPC Class Codes: G06F 11/3037 where the computing system component is a memory, e.g. virtual memory, cache accessing, addressing or allocating within memory systems or architectures G06F12/00; checking stores for correct operation G11C29/00
• CPC Class Codes: G06F 11/3051 Monitoring arrangements for monitoring the configuration of the computing system or of the computing system component, e.g. monitoring the presence of processing resources, peripherals, I/O links, software programs verification or detection of system hardware configuration G06F11/2247
• CPC Class Codes: G06F 11/3082 the data filtering being achieved by aggregating or compressing the monitored data
• CPC Class Codes: G06F 12/0806 Multiuser, multiprocessor or multiprocessing cache systems
• CPC Class Codes: G06F 12/0815 Cache consistency protocols
• CPC Class Codes: G06F 12/0871 Allocation or management of cache space
• CPC Class Codes: G06F 12/0888 using selective caching, e.g. bypass
• CPC Class Codes: G06F 2201/88 Monitoring involving counting
• CPC Class Codes: G06F 2201/885 Monitoring specific for caches
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/284 being distributed
• CPC Class Codes: G06F 2212/461 Sector or disk block
• CPC Class Codes: G06F 2212/466 Metadata, control data
• CPC Class Codes: G06F 2212/601 Reconfiguration of cache memory
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 : Disk arrays, e.g. RAID, JBOD

Abstract

System and method for processing cache metadata from a plurality of cache devices. One or more storage systems may store data blocks to a set of storage devices, each storage system hosting and operating one or more cache devices for caching data blocks of the storage devices. Each cache device may host and implement an agent engine that collects and stores cache metadata for the cache device, the cache metadata describing caching operations of the cache device. A monitor engine receives and aggregates “raw cache metadata” from each of a plurality of cache devices and processes the raw cache metadata to produce processed cache metadata comprising normalized cache metadata (based on activity rate of a cache device), weighted cache metadata, or normalized weighted cache metadata. The processed cache metadata is used by a cache prediction engine to select data blocks for caching to one or more of the cache devices.

Claims

1. A system comprising:

a processor; and

memory operatively coupled to the processor, the memory storing one or more engines configured for execution by the processor, the one or more engines including a monitor engine that when executed, by the processor is operable to;

receive cache metadata from a plurality of cache devices, each cache device configured for caching a plurality of data blocks for a set of storage devices that store the plurality of data blocks, the cache metadata for the cache device describing caching of the plurality of data blocks by the cache device;

normalize the cache metadata of the cache device by dividing a number of block accesses directed to a data block of the plurality of data blocks cached at the cache device by a number of cache accesses for the cache device to produce normalized cached metadata; and

select the data block for caching based on the normalized cache metadata of the cache device.

2. The system of claim 1, wherein an activity rate of the cache device is indicated by the number of cache accesses for the cache device during a predetermined time period.

3. The system of claim 2, wherein the cache metadata specifies the number of block accesses for the selected data block cached by the cache device.

4. The system of claim 2, wherein:

the plurality of cache devices include a first cache device and a second cache device, the first cache device associated with a first cache metadata, and the second cache device associated with a second cache metadata,

the first cache metadata from the first cache device is a first number of block accesses for a first data block cached by the first cache device,

the second cache metadata from the second cache device is a second number of block accesses for the first data block cached by the second cache device, and

wherein the monitor engine when executed to normalize the cache metadata is further operable to;

normalize the first cache metadata and the second cache metadata by;

(i) dividing the first number of block accesses by a first number of cache accesses for the first cache device to produce a first normalized number of block accesses,

(ii) dividing the second number of block accesses by a second number of cache accesses for the second cache device to produce a second normalized number of block accesses, and

(iii) adding the first normalized number of block accesses and the second normalized number of block accesses to produce the normalized cache metadata for the first data block.

5. The system of claim 2, wherein the number of cache accesses comprises a number of read accesses and write accesses, a number of read accesses only, or a number of write accesses only for the cache device during the predetermined time period.

6. The system of claim 1, wherein the monitor engine, when executed is further operable to:

send, to the cache device, at least one parameter for collecting the cache metadata, wherein the at least one parameter is determined based, at least in part, on a number of cache devices in the plurality of cache devices.

7. The system of claim 6, wherein the at least one parameter is modified if a selected cache device is added or removed from the plurality of cache devices.

8. A non-transitory computer readable storage medium containing executable program instructions for execution on a processor and configured to be stored on the non-transitory computer readable storage medium, the program instructions when executed operable to:

receive cache metadata from a plurality of cache devices, each cache device configured to cache a plurality of data blocks for a set of storage devices that store the plurality of data blocks, the cache metadata for the cache device describing caching of the cache device;

normalize the cache metadata of the cache device by dividing a number of block accesses for a data block of the plurality of data blocks cached at the cache device by a number of cache accesses for the cache device to produce normalized cache metadata; and

select the data block for caching based on the normalized cache metadata of the cache device.

9. The non-transitory computer readable medium of claim 8, wherein an activity rate of the cache device is indicated by the number of cache accesses for the cache device during a predetermined time period.

10. The non-transitory computer readable medium of claim 9, wherein the cache metadata from the cache device specifies the number of block accesses for the selected data block cached by the cache device.

11. The non-transitory computer readable medium of claim 9, wherein

the plurality of cache devices includes a first cache device and a second cache device, the first cache device associated with a first cache metadata, and the second cache device associated with a second cache metadata,

the first cache metadata from the first cache device is a first number of block accesses for a first data block cached by the first cache device,

the second cache metadata from the second cache device is a second number of block accesses for the first data block cached by the second cache device;

and

wherein the program instructions when executed to normalize the cache metadata are further operable to;

normalize the first cache metadata and the second cache metadata by;

dividing the first number of block accesses by a first number of cache accesses for the first cache device to produce a first normalized number of block accesses,

dividing the second number of block accesses by a second number of cache accesses for the second cache device to produce a second normalized number of block accesses, and

adding the first normalized number of block accesses and the second normalized number of block accesses to produce the normalized cache metadata for the first data block.

12. The non-transitory computer readable medium of claim 9, wherein the number of cache accesses comprises a number of read accesses and write accesses, a number of read accesses only, or a number of write accesses only for the cache device during the predetermined time period.

13. The non-transitory computer readable medium of claim 8, wherein the program instructions, when executed by the processor, are further operable to:

send, to the cache device, at least one parameter for collecting the cache metadata, wherein the at least one parameter is determined based, at least in part, on a number of cache devices in the plurality of cache devices.

14. The non-transitory computer readable medium of claim 13, wherein the at least one parameter is modified if a selected cache device is added or removed from the plurality of cache devices.

15. A computer-implemented method comprising:

receiving cache metadata from a plurality of cache devices, each cache device configured to cache a plurality of data blocks for a set of storage devices that store the plurality of data blocks, the cache metadata for the cache device describing caching of the plurality of data blocks by the cache device;

normalizing, by a processor of a computer, the cache metadata of the cache device by dividing a number of block accesses for a data block of the plurality of data blocks cached at the cache device by a number of cache accesses for the cache device to produce normalized cache metadata; and

selecting the data block for caching based on the normalized cache metadata.

16. The computer-implemented method of claim 15, wherein an activity rate of the cache device is indicated by the number of cache accesses for the cache device during a predetermined time period.

17. The computer-implemented method of claim 16, wherein the cache metadata from the cache device specifies the number of block accesses for the selected data block cached by the cache device.

18. The computer-implemented method of claim 15, wherein

the plurality of cache devices includes a first cache device and a second cache device, the first cache device associated with a first cache metadata, and the second cache device associated with a second cache metadata;

the first cache metadata from the first cache device is a first number of block accesses for a first data block cached by the first cache device;

the second cache metadata from the second cache device is a second number of block accesses for the first data block cached by the second cache device; and

wherein normalizing the cache metadata further comprises;

normalizing the first cache metadata and the second cache metadata by;

dividing the first number of block accesses by a first number of cache accesses for the first cache device to produce a first normalized number of block accesses;

dividing the second number of block accesses by a second number of cache accesses for the second cache device to produce a second normalized number of block accesses; and

adding the first normalized number of block accesses and the second normalized number of block accesses to produce the normalized cache metadata for the first data block.

19. The computer-implemented method of claim 16, wherein the number of cache accesses comprises a number of read accesses and write accesses, a number of read accesses only, or a number of write accesses only for the cache device during the predetermined time period.

20. The computer-implemented method of claim 15, further comprising:

sending, to the cache device, at least one parameter for collecting the cache metadata, wherein the at least one parameter is determined based, at least in part, on a number of cache devices in the plurality of cache devices.

21. The computer-implemented method of claim 20, wherein the at least one parameter is modified if a selected cache device is added or removed from the plurality of cache devices.