Data access request monitoring to reduce system resource use for background operations

Patent metadata

Field	Value
Publication number	US-9367245-B2
Application number	US-201313871783-A
Country	US
Kind code	B2
Filing date	Apr 26, 2013
Priority date	Apr 26, 2013
Publication date	Jun 14, 2016
Grant date	Jun 14, 2016

Abstract

An I/O processing stack includes a proxy that can provide processing services for access requests to initialized and uninitialized storage regions. For a write request, the proxy stores write information in a write metadata repository. If the write is requested for an address in an initialized storage region of the storage system, the proxy performs a write to the initialized region based on region information in the write I/O access request. If the write is requested for an address in an uninitialized storage region of the storage system, the proxy performs an on-demand initialization of the storage region and then performs a write to the storage region based on region information provided by the proxy.

First claim

What is claimed is:

1. A method comprising:
receiving an I/O (input/output) access request by a proxy layer of an I/O processing stack in a storage server of a storage system having initialized storage space and uninitialized storage space;
storing host write information for a write I/O access request in a host write metadata repository managed by the proxy layer;
determining if an address of the write I/O access request corresponds to an initialized storage region of the storage system or an uninitialized storage region of the storage system; and
when the address corresponds to an uninitialized storage region, performing an on-demand initialization of the storage region, and performing a write of the write I/O access request based on region information provided by the proxy layer.

2. The method of claim 1 , wherein the host write metadata repository comprises a delta log.

3. The method of claim 1 , wherein receiving the I/O access request further comprises determining if the I/O access request is a read I/O access request or a write I/O access request.

4. The method of claim 3 , wherein in response to determining that the I/O access request is a read I/O access request, determining if an address of the read I/O request corresponds to an initialized storage region of the storage system or an uninitialized storage region of the storage system, wherein when the address corresponds to an uninitialized storage region, returning zeroed data from the proxy layer without accessing the uninitialized storage region.

5. The method of claim 1 , wherein the uninitialized storage region is uninitialized due to execution of a background parity generation process.

6. The method of claim 5 , further comprising determining that execution of the background process has reached a threshold execution point; and disabling the proxy layer in response to determining that the background process has completed execution.

7. The method of claim 1 , further comprising determining that the proxy layer has initialized a threshold amount of a volume, and triggering start of a background initialization process in response to determining that the threshold amount of the volume has been reached.

8. The method of claim 1 , wherein the background process includes a feature for synchronizing data over a network link, and further comprising:
determining whether host write metadata exists for a data block; and
copying a data block over the network link when host write metadata exists for the data block; and
not copying a data block over the network link when no host write metadata exists for the data block.

9. The method of claim 1 , wherein initializing the storage region when the address corresponds to an uninitialized storage region comprises writing zeroes to the storage region prior to committing a write to disk.

10. The method of claim 1 , wherein initializing the storage region when the address corresponds to an uninitialized storage region comprises writing the write I/O access request to cache and filling out the storage region associated with the write I/O access request with zeroes.

11. The method of claim 10 , wherein for a subsequent write I/O access request to the same storage region, writing the subsequent write I/O access request to the cache, overwriting the zeroes.

12. A non-transitory machine readable medium having stored thereon instructions for performing a method comprising machine executable code which when executed by at least one machine, causes the machine to:
receive an I/O (input/output) access request by a proxy layer of an I/O processing stack having initialized storage space and uninitialized storage space;
store host write information for a write I/O access request in a host write metadata repository managed by the proxy layer; determining if an address of the write I/O access request corresponds to an initialized storage region or an uninitialized storage region;
when the address corresponds to an initialized storage region, perform a write of the write I/O access request to the initialized storage region based on region information in the write I/O access request; and
when the address corresponds to an uninitialized storage region, perform an on-demand initialization of the uninitialized storage region, and perform a write of the write I/O access request based on region information provided by the proxy layer.

13. The non-transitory machine readable medium of claim 12 having further machine executable code that causes the machine to:
determine if the I/O access request is a read I/O access request or a write I/O access request; and
in response to determining that the I/O access request is a read I/O access request;
determine if an address of the read I/O request corresponds to an initialized storage region or an uninitialized storage region;
when the address corresponds to an initialized storage region, perform a read of the initialized storage region based on the read I/O request; and
when the address corresponds to an uninitialized storage region, return zeroed data from the proxy layer without accessing the uninitialized storage region.

14. The non-transitory machine readable medium of claim 12 having further machine executable code that causes the machine to:
move only user data for execution of a background process, including one of a disk reconstruction process, volume copy, or an asynchronous remote volume mirroring process.

15. The non-transitory machine readable medium of claim 12 having further machine executable code that causes the machine to:
determine that the proxy layer has initialized a threshold amount of a volume, and triggering start of a background initialization process in response to determining that the threshold amount of the volume has been reached.

16. A computing device comprising:
a memory containing machine readable medium comprising machine executable code having stored thereon instructions for performing a method of accessing data in a storage system;
a processor coupled to the memory, the processor configured to execute the machine executable code to cause the processor to:
store write information for a write I/O access request in a metadata repository; and
determine if an address of the write I/O access request corresponds to an initialized storage region of the storage system or an uninitialized storage region of the storage system,
wherein when the address corresponds to the uninitialized storage region, a write capture proxy of an I/O (input/output) transaction processing stack performs an on-demand initialization of the uninitialized storage region and a write of the write I/O access request based on region information for the write I/O access request.

17. The computing device of claim 16 , wherein the write capture proxy further determines if an I/O access request is a read I/O access request.

18. The computing device of claim 17 , wherein in response to determining that the I/O access request is the read I/O access request, the write capture proxy determines if an address of the read I/O request corresponds to the initialized storage region of the storage system or the uninitialized storage region of the storage system, wherein when the address corresponds to the uninitialized storage region, the write capture proxy returns zeroed data without accessing the uninitialized storage region.

19. The computing device of claim 16 , wherein the uninitialized storage region is uninitialized due to execution of a background process, including one of a disk reconstruction process, a back

Assignees

• Netapp Inc

Inventors

• Sangapu Satish
• Sun Wei
• Moyer Keith
• Binford Charles

Classifications

• G06F11/2082

  Data synchronisation · CPC title

• G06F2212/466

  Metadata, control data · CPC title

• G06F11/2071

  using a plurality of controllers · CPC title

• G06F12/0875

  with dedicated cache, e.g. instruction or stack · CPC title

• G06F12/0866

  for peripheral storage systems, e.g. disk cache · CPC title