System and method for lockless reading of metadata pages

Patent metadata

Field	Value
Publication number	US-11599460-B2
Application number	US-202117237398-A
Country	US
Kind code	B2
Filing date	Apr 22, 2021
Priority date	Apr 22, 2021
Publication date	Mar 7, 2023
Grant date	Mar 7, 2023

Abstract

A method, computer program product, and computing system for assigning a plurality of unique sequential identifiers to a plurality of tablets in a cache memory system. One or more metadata deltas associated with a metadata page stored in a storage array may be written to the plurality of tablets in the cache memory system. Each metadata delta stored in at least one tablet of the plurality of tablets may be written to the metadata page stored in the storage array, thus defining one or more destage tablets. A largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the one or more destage tablets, may be written to the storage array, thus defining a current tablet identifier for the metadata page.

First claim

What is claimed is:

1. A computer-implemented method, executed on a computing device, comprising:
assigning a plurality of unique sequential identifiers to a plurality of tablets in a cache memory system;
writing one or more metadata deltas associated with a metadata page stored in a storage array, to the plurality of tablets in the cache memory system;
writing each metadata delta stored in at least one tablet of the plurality of tablets, to the metadata page stored in the storage array, thus defining one or more destage tablets; and
writing a largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the one or more destage tablets, to the storage array, thus defining a current tablet identifier for the metadata page;
performing a read operation on the metadata page based upon, at least in part, the current tablet identifier for the metadata page, wherein performing the read operation includes:
reading the metadata page from the storage array;
reading the current tablet identifier for the metadata page from the storage array;
identifying a next tablet from the plurality of tablets based upon, at least in part, the current tablet identifier read from the storage array;
applying each metadata delta stored in the next tablet from the plurality of tablets, to the metadata page read from the storage array; and
applying each metadata delta stored in each tablet of the plurality of tablets, to the metadata page read from the storage array.

2. The computer implemented method of claim 1 , further comprising:
writing a largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the plurality of tablets, to the storage array, thus defining an updated tablet identifier.

3. The computer implemented method of claim 1 , further comprising:
writing the metadata page to the cache memory system.

4. A computer program product residing on a non-transitory computer readable medium having a plurality of instructions stored thereon which, when executed by a processor, cause the processor to perform operations comprising:
assigning a plurality of unique sequential identifiers to a plurality of tablets in a cache memory system;
writing one or more metadata deltas associated with a metadata page stored in a storage array, to the plurality of tablets in the cache memory system;
writing each metadata delta stored in at least one tablet of the plurality of tablets, to the metadata page stored in the storage array, thus defining one or more destage tablets; and
writing a largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the one or more destage tablets, to the storage array, thus defining a current tablet identifier for the metadata page;
performing a read operation on the metadata page based upon, at least in part, the current tablet identifier for the metadata page, wherein performing the read operation includes:
reading the metadata page from the storage array;
reading the current tablet identifier for the metadata page from the storage array; and
identifying a next tablet from the plurality of tablets based upon, at least in part, the current tablet identifier read from the storage array;

applying each metadata delta stored in the next tablet from the plurality of tablets, to the metadata page read from the storage array; and
applying each metadata delta stored in each tablet of the plurality of tablets, to the metadata page read from the storage array.

5. The computer program product of claim 4 , wherein the operations further comprise:
writing a largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the plurality of tablets, to the storage array, thus defining an updated tablet identifier.

6. The computer program product of claim 4 , wherein the operations further comprise:
writing the metadata page to the cache memory system.

7. A computing system comprising:
a memory; and
a processor configured to assign a plurality of unique sequential identifiers to a plurality of tablets in a cache memory system, wherein the processor is further configured to write one or more metadata deltas associated with a metadata page stored in a storage array, to the plurality of tablets in the cache memory system, wherein the processor is further configured to write each metadata delta stored in at least one tablet of the plurality of tablets, to the metadata page stored in the storage array, thus defining one or more destage tablets, and wherein the processor is configured to write a largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the one or more destage tablets, to the storage array, thus defining a current tablet identifier for the metadata page, wherein the processor is further configured to perform a read operation on the metadata page based upon, at least in part, the current tablet identifier for the metadata page, wherein performing the read operation includes: reading the metadata page from the storage array, reading the current tablet identifier for the metadata page from the storage array, and identifying a next tablet from the plurality of tablets based upon, at least in part, the current tablet identifier read from the storage array, wherein the processor is further configured to apply each metadata delta stored in the next tablet from the plurality of tablets, to the metadata page read from the storage array, and wherein the processor is further configured to apply each metadata delta stored in each tablet of the plurality of tablets, to the metadata page read from the storage array.

8. The computing system of claim 7 , wherein the processor is further configured to:
write a largest unique sequential identifier from the plurality of unique sequential identifiers assigned to the plurality of tablets, to the storage array, thus defining an updated tablet identifier.

Assignees

• Emc Ip Holding Co Llc

Inventors

• Derzhavetz Jenny
• Shveidel Vladimir
• Zalstein Dror
• David Bar

Classifications

• G06F3/061

  Improving I/O performance · CPC title

• G06F2212/1024

  Latency reduction · CPC title

• G06F2212/262

  configured as RAID · CPC title

• G06F12/0802 Primary

  Addressing of a memory level in which the access to the desired data or data block requires associative addressing means, e.g. caches · CPC title

• G06F3/0679

  Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP] · CPC title