Method, device, and program product for reducing delay in I/O processing due to mirroring of cache data

Patent metadata

Field	Value
Publication number	US-11385796-B2
Application number	US-201916575466-A
Country	US
Kind code	B2
Filing date	Sep 19, 2019
Priority date	Oct 31, 2018
Publication date	Jul 12, 2022
Grant date	Jul 12, 2022

Abstract

Techniques perform storage management. Such techniques involve: in response to receiving, at a first processor of a storage system, a write request from a host for writing user data, caching the user data in a first cache of the first processor, and generating cache metadata in the first cache, the cache metadata including information associated with writing the user data; sending the user data and the cache metadata to a second cache of a second processor, for the second processor to perform, in the second cache, data processing related to cache mirroring by the second processor; and sending, to the host, an indication of completion of the write request, without waiting for the second processor to complete the data processing. Such techniques can improve system performance such as reducing latency, and shortening length of the I/O handling path of write request.

First claim

We claim:

1. A method of storage management, comprising:
receiving, at a second processor of a storage system, user data and cache metadata from a first cache of a first processor of the storage system, the cache metadata comprising information associated with writing the user data to the storage system;
preprocessing the cache metadata, such that the user data is accessible to a host via the second processor; and
performing, in a second cache of the second processor, data processing related to cache mirroring based on the user data and the cache metadata;

wherein preprocessing the cache metadata comprises:
moving the cache metadata from a receiving buffer of the second cache to a queue of cache metadata accessible to the host.

2. The method of claim 1 , wherein receiving the user data and the cache metadata comprises:
transferring the user data from a first physical page of the first cache to a second physical page of the second cache; and
buffering the cache metadata to the receiving buffer of the second cache.

3. The method of claim 1 , wherein moving the cache metadata to the queue of cache metadata comprises:
in response to locking successfully a cache page indicated by the cache metadata, moving the cache metadata to a queue of cache metadata to be processed, to wait for processing by the second processor; and
in response to failing to lock the cache page, moving the cache metadata to a waiting queue of cache metadata, to wait for locking the cache page by the second processor for the cache metadata.

4. The method of claim 1 , wherein performing the data processing comprises:
adding a physical page storing the user data to a cache page indicated by the cache metadata.

5. The method of claim 1 , wherein performing the data processing comprises:
waking up a background thread to perform the data processing.

6. The method of claim 1 , further comprising:
in response to receiving an I/O request from the host, preprocessing all cache metadata in the second cache that has not been preprocessed; and
handling the I/O request.

7. The method of claim 1 , wherein receiving the cache metadata comprises:
receiving a cache metadata message comprising the cache metadata and recovery information for recovering the cache metadata message during a failure recovery.

8. The method of claim 7 , wherein the recovery information comprises at least one of the following: a processing state, a sending serial number, and a checksum of the cache metadata message.

9. The method of claim 8 , further comprising at least one of the follows:
in response to completion of the preprocessing, changing the processing state from an initial value of “valid” to “preprocessed;”
in response to the data processing being in progress, setting the processing state to “processing;” and
in response to the completion of the data processing, setting the processing state to “invalid.”

10. The method of claim 7 , further comprising:
in response to the storage system recovering from a failure, recovering the cache metadata message based on the recovery information.

11. The method of claim 10 , wherein recovering the cache metadata message comprises at least one of the following:
determining, based on the processing state, that the cache metadata message is required to be recovered;
determining, based on the sending serial number, a sequence of the cache metadata message and a further recovered cache metadata message; and
checking integrity of the cache metadata message based on the checksum.

12. The method of claim 1 wherein receiving the user data and the cache metadata from the first cache of the first processor includes:
receiving at least some of the data through a communication manager interface (CMI) that connects the first processor and the second processor.

13. An electronic device, comprising:
at least two processors; and
at least one memory storing computer program instructions, the at least one memory and the computer program instructions being configured, together with the at least two processors, to cause the electronic device to:
receive, at a second processor, user data and cache metadata from a first cache of a first processor, the cache metadata comprising information associated with writing the user data to the storage system;
preprocess the cache metadata, such that the user data is accessible to a host via the second processor; and
performing, in a second cache of the second processor, data processing related to cache mirroring based on the user data and the cache metadata;

wherein preprocessing the cache metadata comprises:
moving the cache metadata from a receiving buffer of the second cache to a queue of cache metadata accessible to the host.

14. The electronic device of claim 13 , wherein performing the data processing comprises:
waking up a background thread to perform the data processing.

15. The electronic device of claim 13 , wherein receiving the cache metadata comprises:
receiving a cache metadata message comprising the cache metadata and recovery information for recovering the cache metadata message during a failure recovery.

16. The electronic device of claim 15 , wherein the recovery information comprises at least one of the following: a processing state, a sending serial number, and a checksum of the cache metadata message.

17. The electronic device of claim 16 , wherein the instructions further cause the electronic device to perform at least one of the following:
in response to completion of the preprocessing, change the processing state from an initial value of “valid” to “preprocessed;”
in response to the data processing being in progress, set the processing state to “processing;” and
in response to the completion of the data processing, set the processing state to “invalid.”

18. A computer program product having a non-transitory computer readable medium which stores a set of instructions to perform storage management; the set of instructions, when carried out by computerized circuitry, causing the computerized circuitry to perform a method of:
receiving, at a second processor of a storage system, user data and cache metadata from a first cache of a first processor of the storage system, the cache metadata comprising information associated with writing the user data to the storage system;
preprocessing the cache metadata, such that the user data is accessible to a host via the second processor; and
performing, in a second cache of the second processor, data processing related to cache mirroring based on the user data and the cache metadata;

wherein preprocessing the cache metadata comprises:
moving the cache metadata from a receiving buffer of the second cache to a queue of cache metadata accessible to the host.

19. The computer program product of claim 18 , wherein performing the data processing comprises:
waking up a background thread to perform the data processing.

20. The computer program product of claim 18 , wherein receiving the cache metadata comprises:
receiving a cache metadata message comprising the cache metadata and recovery information for recovering the cache metadata message during a failure recovery.

21. The computer program product of claim 20 , wherein the recovery information comprises at least one of the following: a processing state, a sending serial number, and a checksum of the cache metadata message.

22. The computer program product of claim 21 , wherein the method furth

Assignees

• Emc Ip Holding Co Llc

Inventors

• Liu Yousheng
• Jia Ruiyong
• Xu Xinlei

Classifications

• G06F2212/262

  configured as RAID · CPC title

• G06F11/2082

  Data synchronisation · CPC title

• G06F9/30123

  according to context, e.g. thread buffers · CPC title

• G06F3/0689

  Disk arrays, e.g. RAID, JBOD · CPC title

• G06F12/0868 Primary

  Data transfer between cache memory and other subsystems, e.g. storage devices or host systems · CPC title