Dropped write error detection

Patent metadata

Field	Value
Publication number	US-11080136-B2
Application number	US-202016734449-A
Country	US
Kind code	B2
Filing date	Jan 6, 2020
Priority date	Jan 6, 2020
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A computer-implemented method for dropped write error detection is proposed. In the method, a read request for a stride stored in an array of storage drives is received. The stride includes segments of a data and a first parity associated with the data spreading across the storage drives in the array of the storage drives. In response to the read request being a predefined sequential read request and a state of the stride being a first state, a parity check is performed on the stride. The first state indicates that no parity check has been performed after the data is written into the array of storage drives. The state of the stride is changed to a second state, and the second state is different with the first state.

First claim

What is claimed is:

1. A computer-implemented method, comprising:
receiving, by one or more processing units, a read request for a stride stored in an array of storage drives, wherein the stride includes segments of a data and a first parity associated with the data spreading across the storage drives in the array of the storage drives;
in response to the read request being a predefined sequential read request and a state of the stride being a first state, performing, by one or more processing units, a parity check on the stride, wherein the first state indicating that no parity check has been performed after the data is written into the array of storage drives; and
changing, by one or more processing units, the state of the stride to a second state, the second state being different with the first state.

2. The method of claim 1 , further comprising:
determining, by one or more processing units, whether it's time to perform a parity check on the stride according to a cyclic schedule associated with the stride;
in response to determining that it's time to perform a parity check on the stride and the state of the stride being the first state, performing, by one or more processing units, a parity check on the stride; and
changing, by one or more processing units, the state of the stride to the second state.

3. The method of claim 2 , wherein the cyclic schedule associated with the stride is based on a heat level of the stride indicating an access frequency of the stride.

4. The method of claim 2 , further comprising:
in response to determining that it's time to perform a parity check on the stride and the state of the stride not being the first state, skipping, by one or more processing units, the parity check on the stride.

5. The method of claim 1 , further comprising:
writing, by one or more processing units, a second data and a second parity associated with the second data to the stride; and
setting, by one or more processing units, the state of the stride to the first state.

6. The method of claim 1 , wherein the parity check on the stride is performed by:
reading the data and the first parity associated with the data from the stride;
generating a second parity based on the data; and
comparing the first parity with the second parity to check integrity of the data in the stride.

7. The method of claim 1 , wherein the state of the stride is indicated by a bit corresponding to the stride in a stride scan bitmap, and wherein a first value of the bit indicates the first state and a second value of the bit indicates the second state.

8. The method of claim 1 , further comprising:
returning, by one or more processing units, the data in the stride to a host according to the read request,
wherein the step of returning the data in the stride and the step of performing the parity check on the stride are performed asynchronously.

9. The method of claim 1 , further comprising:
in response to the result of the parity check on the stride being positive, returning, by one or more processing units, the data in the stride to a host according to the read request.

10. A computer program product (CPP) comprising a computer readable storage medium having program instructions embodied therewith, the program instructions being executable by a device to perform a method comprising:
receiving a read request for a stride stored in an array of storage drives, wherein the stride includes segments of a data and a first parity associated with the data spreading across the storage drives in the array of the storage drives;
in response to the read request being a predefined sequential read request and a state of the stride being a first state, performing a parity check on the stride, wherein the first state indicating that no parity check has been performed after the data is written into the array of storage drives; and
changing the state of the stride to a second state, the second state being different with the first state.

11. The CPP of claim 10 further comprising a set of processor(s) for executing the program instructions, wherein the CPP is in the form of a computer system (CS).

12. The CPP of claim 10 , the method further comprises:
determining whether it's time to perform a parity check on the stride according to a cyclic schedule associated with the stride;
in response to determining that it's time to perform a parity check on the stride and the state of the stride being the first state, performing a parity check on the stride; and
changing the state of the stride to the second state.

13. The CPP of claim 12 , wherein the cyclic schedule associated with the stride is based on a heat level of the stride indicating an access frequency of the stride.

14. The CPP of claim 10 , wherein the state of the stride is indicated by a bit corresponding to the stride in a stride scan bitmap, and wherein a first value of the bit indicates the first state and a second value of the bit indicates the second state.

15. A computer implemented method (CIM) for use with a plurality of cooperatively operating storage devices that collectively store a plurality of strides of data, the CIM comprising:
writing a first stride of the plurality of strides to the plurality of cooperatively operating storage devices, with the first stride including substantive data and metadata including information indicating that no parity check has been performed since the substantive data was written to the plurality of cooperatively operating storage devices;
receiving an access request to access the substantive data of the first stride;
determining that the first stride has not been subject to a parity check since the first stride was written to the plurality of cooperatively operating storage devices based on the metadata of the first stride; and
responsive to the access request and further responsive to the determination that the first stride has not been subject to a parity check:
performing a parity check on the first stride to determine that the first stride has been stored correctly,
responsive to the determination that the substantive data of the first stride has been stored correctly and further responsive to the receipt of the access request, providing access to the substantive data of the first stride, and
changing the metadata of the first stride to indicate that a parity check has been performed on the first stride.

16. The CIM of claim 15 wherein the metadata is in the form of a set of bit(s) included within a stride scan bitmap.

17. The CIM of claim 15 the metadata indicates whether a parity check has been performed by a bit corresponding to the first stride in a stride scan bitmap.

18. The CIM of claim 17 wherein:
a first value of the bit indicates that a parity check has not been done; and
a second value of the bit indicates that a parity check has been done.

Assignees

• IBM

Inventors

• Lyu Gang
• Gu Jun
• Zhou Hong

Classifications

• G06F11/1004

  to protect a block of data words, e.g. CRC or checksum (G06F11/1076 takes precedence; security arrangements for protecting computers or computer systems against unauthorized activity G06F21/00) · CPC title

• G06F3/0683 Primary

  Plurality of storage devices · CPC title

• G06F3/0634

  by changing the state or mode of one or more devices · CPC title

• G06F3/0619

  in relation to data integrity, e.g. data losses, bit errors · CPC title

• G06F3/0644

  Management of space entities, e.g. partitions, extents, pools · CPC title