Operating shingled magnetic recording device

Patent metadata

Field	Value
Publication number	US-10108545-B2
Application number	US-201615263964-A
Country	US
Kind code	B2
Filing date	Sep 13, 2016
Priority date	Sep 17, 2015
Publication date	Oct 23, 2018
Grant date	Oct 23, 2018

Abstract

The present application provides a method and apparatus of operating a shingled magnetic recording device that comprises a random access zone in which data is randomly readable and writable and a sequential access zone in which data is only sequentially readable and writable, and the sequential access zone is logically split into a plurality of banks operated independent of each other and storing a mapping from logical block addresses to physical block addresses in the random access zone; storing, in each bank of the plurality of banks in the sequential access zone, a respective part of a mapping from physical block addresses to logical block addresses; and operating the shingled magnetic recording device based on the mapping from logical block addresses to physical block addresses and the mapping from physical block addresses to logical block addresses.

First claim

What is claimed is:

1. A method of operating a shingled magnetic recording device, the device including a random access zone wherein data is randomly readable and writable and a sequential access zone wherein data is only sequentially readable and writable, the sequential access zone being logically split into a plurality of banks operated independent of each other, the method comprising:
storing a mapping from logical block addresses to physical block addresses in the random access zone;
storing, in each of the plurality of banks in the sequential access zone, a respective part of a mapping from physical block addresses to logical block addresses; and
operating the shingled magnetic recording device based on the mapping from logical block addresses to physical block addresses and the mapping from physical block addresses to logical block addresses;
wherein the random access zone further stores metadata for operating the shingled magnetic recording device, the metadata at least comprising one or more from the group consisting of: a free bank list, a used bank list, a plurality of counters maintained for each bank respectively, a next available segment in a current working bank, and a persisted write-stamp.

2. The method according to claim 1 , wherein the mapping from logical block addresses to physical block addresses is stored in a buffer for the random access zone.

3. The method according to claim 1 , wherein a user data predicted to be modified frequently is directly stored in the random access zone.

4. The method according to claim 1 , wherein each of the plurality of banks is split into a plurality of segments, each segment includes a segment header and a plurality of blocks, each of the plurality of blocks is used as a minimum unit for data reading/writing, and
wherein the respective part of the mapping from physical block addresses to logical block addresses is stored in the segment header.

5. The method according to claim 4 , wherein operating the shingled magnetic recording device comprises:
in response to receiving a data write request containing a logical block address and user data, determining a physical block address corresponding to the target logical block address based on the mapping from logical block addresses to physical block addresses;
determining a bank corresponding to the physical block address; and
updating a counter maintained for the bank.

6. The method according to claim 5 , wherein operating the shingled magnetic recording device comprises:
determining a bank corresponding to the counter with a maximum value;
identifying valid data blocks and invalid data blocks in the determined bank;
reading a user data in the valid data blocks;
rewriting the user data read from the valid data blocks into a current bank; and
moving the determined bank into a free bank list.

7. The method according to claim 6 , wherein identifying valid data blocks and invalid data blocks in the determined bank comprises:
reading segment headers of respective segments included in the determined bank;
translating mapping from physical block addresses to logical block addresses in the segment headers into respective mapping from logical block addresses to physical block addresses;
comparing the mapping from logical block addresses to physical block addresses translated for the segment headers with the respective mapping from logical block addresses to physical block addresses in the random access zone, respectively;
identifying the blocks in segments corresponding to the segment headers as valid data blocks if the mapping from logical block addresses to physical block addresses translated for the segment headers is identical with the respective mapping from logical block addresses to physical block addresses in the random access zone; and
identifying the blocks in the segments corresponding to the segment headers as invalid data blocks if the mapping from logical block addresses to physical block addresses translated for the segment headers is not identical with the respective mapping from logical block addresses to physical block addresses in the random access zone.

8. The method according to claim 1 , wherein operating the shingled magnetic recording device comprises:
in response to receiving a data write request containing a target logical block address and the user data, attaching the user data to an end of a currently working bank; and
updating the mapping from logical block addresses to physical block addresses and the respective part of the mapping from physical block addresses to logical block addresses.

9. The method according to claim 8 , wherein operating the shingled magnetic recording device further comprises:
in response to the currently working bank being full,
adding the currently working bank into the used bank list, and
selecting a new bank from the free bank list as a new currently working bank.

10. The method according to claim 1 , wherein operating the shingled magnetic recording device comprises:
in response to receiving a data read request containing the target logical block address, determining a plurality of physical block address ranges corresponding to the target logical block address based on the mapping from logical block addresses to physical block addresses; and
performing respective data reading for each of the plurality of physical block address ranges.

11. The method according to claim 1 , wherein operating the shingled magnetic recording device comprises:
recovering the mapping from logical block addresses to physical block addresses in the random access zone based on the mapping from physical block addresses to logical block addresses stored in the sequential access zone upon determination of at least one of a system crash or a power failure.

12. The method according to claim 11 , wherein recovering the mapping from logical block addresses to physical block addresses in the random access zone based on the mapping from physical block addresses to logical block addresses stored in the sequential access zone comprises:
obtaining, based on write-stamps in segment headers of respective segments included in the banks and a persisted write-stamp in metadata, the mapping from physical block addresses to logical block addresses included in segment headers corresponding to write-stamps larger than the persisted write-stamp; and
recovering the mapping from logical block addresses to physical block addresses in the random access zone based on the obtained mapping from physical block addresses to logical block addresses.

13. The method according to claim 12 , wherein obtaining, based on write-stamps in segment headers of respective segments included in the banks and a persisted write-stamp in metadata, the mapping from physical block addresses to logical block addresses included in segment headers corresponding to write-stamps larger than the persisted write-stamp comprises:
reading a first segment header and a last segment header in each bank;
determining, based on a comparison of the write-stamps read in the first segment header and the last segment header with the persisted write-stamp in the metadata, whether the bank is available for recovering the mapping from logical block addresses to physical block addresses; and
obtaining the mapping from physical block addresses to logical block addresses in the segment header in the bank that is available for recovering the mapping from logical block addresses to physical block addresses.

14. An apparatus of operating a shingled magnetic recording device, the device including a random access zone wherein data is randomly readable an

Assignees

• Emc Corp
• EMC IP Holding Company

Inventors

• Han Geng
• Gao Jian
• Xiao Huibing
• Dong Jibing
• Zhang Lester Ming

Classifications

• G06F12/0292 Primary

  using tables or multilevel address translation means (G06F12/023 takes precedence; address translation in virtual memory systems G06F12/10) · CPC title

• G06F3/064

  Management of blocks · CPC title

• G06F3/0676

  Magnetic disk device · CPC title

• G06F3/0659

  Command handling arrangements, e.g. command buffers, queues, command scheduling · CPC title

• G06F3/0626

  Reducing size or complexity of storage systems · CPC title