CACHE DATA PLACEMENT FOR COMPRESSION IN DATA STORAGE SYSTEMS

• US 20160335188A1
• Filed: 06/30/2015
• Published: 11/17/2016
• Est. Priority Date: 06/27/2014
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Romanovskiy, Alexey Valentinovich
• Granted Patent: US 10,466,932 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0261 using reference counting
• CPC Class Codes: G06F 12/0855 Overlapped cache accessing, e.g. pipeline G06F12/0846 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 12/0871 Allocation or management of cache space
• CPC Class Codes: G06F 12/0873 Mapping of cache memory to specific storage devices or parts thereof
• CPC Class Codes: G06F 12/123 with age lists, e.g. queue, most recently used [MRU] list or least recently used [LRU] list
• CPC Class Codes: G06F 2212/1024 Latency reduction
• CPC Class Codes: G06F 2212/1044 Space efficiency improvement
• CPC Class Codes: G06F 2212/281 Single cache
• CPC Class Codes: G06F 2212/313 In storage device
• CPC Class Codes: G06F 2212/401 Compressed data
• CPC Class Codes: G06F 2212/461 Sector or disk block
• CPC Class Codes: G06F 2212/608 Details relating to cache mapping
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 2212/7207 management of metadata or control data
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0652 : Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0661 : Format or protocol conversion 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 3/0673 : Single storage device

Abstract

A technique for managing data storage in a data storage system is disclosed. Data blocks are written to a data storage system cache, pluralities of the data blocks being organized into cache macro blocks, the IO cache macro blocks having a fixed size. Access requests for the data blocks are processed, wherein processing includes generating block access statics. Using access statics, data blocks stored in the cache macroblocks having block a access times that overlap are identified. Data blocks identified as having overlapping access times are rearranged into one or more overlap cache macroblocks. Data storage system cache memory is arranged into multiple input/output (IO) cache macroblocks, where a first set of IO cache macroblocks are configured as compressed IO cache macro blocks, each compressed IO cache macro block storing a plurality of variable sized compressed IO data blocks, and a second set of IO cache macroblocks are configured as non-compressed IO cache macroblocks, each non-compressed IO cache macroblock storing a plurality of fixed sized non-compressed IO data blocks. A write request is receive at the data storage system. If the IO data associated with the write request is determined to be compressible, the IO data is compressed in-line and written to an IO data block in a compressed IO cache macroblock, otherwise non-compressed IO data is written to an IO data block in a non-compressed IO cache macroblock.

Claims

1. A method for managing data storage in a data storage system, the method comprising:

writing data blocks to a data storage system cache, pluralities of the data blocks being organized into cache macroblocks, the IO cache macroblocks having a fixed size;

processing access requests for the data blocks, wherein processing includes generating block access statics;

identifying, via access statics, data blocks stored in the cache macroblocks having block a access times that overlap; and

rearranging data blocks identified as having overlapping access times into one or more overlap cache macroblocks.

2. The method of claim 1, further comprising:

writing the one or more overlap cache macroblocks to primary persistent storage.

3. The method of claim 1, further comprising:

writing the one or more overlap cache macroblocks to primary persistent storage and deleting the generated data block access statics.

4. The method of claim 1, further comprising:

writing the one or more overlap cache macroblocks to back-end hard disk drives.

5. The method of claim 1, further comprising:

determining that at least a portion of persistent storage comprises flash memory devices and preventing copying data blocks to the portion of persistent storage comprising flash memory devices.

6. The method of claim 1, further comprising:

deleting the one or more overlap cache macroblocks if they are not written to persistent storage.

7. The method of claim 1, further comprising:

creating a cache macroblock data structure, wherein the cache macroblock data structure includes metadata describing access characteristics of the IO data blocks organized therein.

9. The system of claim 7, further comprising:

write the one or more overlap cache macroblocks to primary persistent storage.

10. The system of claim 7, further comprising:

write the one or more overlap cache macroblocks to primary persistent storage and deleting the generated data block access statics.

11. The system of claim 7, further comprising:

write the one or more overlap cache macroblocks to back-end hard disk drives.

12. The system of claim 7, further comprising:

determine that at least a portion of persistent storage comprises flash memory devices and preventing copying data blocks to the portion of persistent storage comprising flash memory devices.

13. The system of claim 7, further comprising:

delete the one or more overlap cache macroblocks if they are not written to persistent storage.

14. The system of claim 7, further comprising:

create a cache macroblock data structure, wherein the cache macroblock data structure includes metadata describing access characteristics of the IO data blocks organized therein.

8. A system for managing data storage in a data storage system, the system comprising a special purpose storage processor and memory configured to:

write data blocks to a data storage system cache, pluralities of the data blocks being organized into cache macroblocks, the IO cache macroblocks having a fixed size;

process access requests for the data blocks, wherein processing includes generating block access statics;

identify, via access statics, data blocks stored in the cache macroblocks having block a access times that overlap; and

rearrange data blocks identified as having overlapping access times into one or more overlap cache macroblocks.