Weighting of read commands to zones in storage devices

Patent metadata

Field	Value
Publication number	US-11210027-B2
Application number	US-202016847352-A
Country	US
Kind code	B2
Filing date	Apr 13, 2020
Priority date	Apr 13, 2020
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

The present disclosure generally relates to methods of operating storage devices. The storage device comprises a controller and a storage unit divided into a plurality of zones, each zone comprises a plurality of erase blocks. Data is written to an erase block of a zone to a program point that is less than the writeable capacity of the erase block. The data in the erase block is associated with various read weights dependent on the location of the data relative to the program point. Data stored closer to the program point has a higher read weight than data stored closer to the beginning of the erase block. The read weights indicate an error susceptibility of the data. When one or more read commands are received, the read weights of the data being read are accumulated to estimate the bit error accumulation until a predetermined value is reached.

First claim

What is claimed is:

1. A storage device, comprising:
a non-volatile storage unit, wherein a capacity of the non-volatile storage unit is divided into a plurality of zones, wherein the non-volatile storage unit comprises a plurality of dies, each of the plurality of dies comprising a plurality of erase blocks, and wherein each zone of the plurality of zones comprises a plurality of erase blocks; and
a controller coupled to the non-volatile storage unit, wherein the controller is configured to:
write data associated with one or more first commands to a first zone of the plurality of zones sequentially, the first zone having a writeable capacity, wherein the data associated with the one or more first commands partially fills the first zone to a first program point less than the writeable capacity; and
receive one or more read commands to read the data from the first zone non-sequentially, wherein:
a weight of a plurality of initial weights is applied to each of the one or more read commands, the plurality of initial weights each having a value indicating a level of susceptibility to read errors based on a closeness of the data being read to the first program point,
the values of at least two weights of the plurality of initial weights applied to the one or more read commands are different,
a first initial weight of the plurality of initial weights having a first level of susceptibility to read errors is associated with a first number of wordlines in the first zone disposed closest to a zone starting point of the first zone,
a second initial weight of the plurality of initial weights having a second level of susceptibility to read errors higher than the first level is associated with a second number of wordlines in the first zone disposed closest to the first program point, and
the first number of wordlines is greater than the second number of wordlines.

2. The storage device of claim 1 , wherein the data associated with the one or more commands is written to a partially full first erase block of the first zone, and wherein the one or more read commands are to read the data stored in the first erase block.

3. The storage device of claim 2 , wherein the controller is further configured to: close the first erase block when a sum of the weights applied to the one or more read commands accumulates to a predetermined value.

4. The storage device of claim 1 , wherein the weight of a read command is higher the closer the read command is to the first program point.

5. The storage device of claim 1 , wherein the controller is further configured to:
write data associated with one or more second commands to the first zone sequentially, wherein the data associated with the one or more second commands partially fills the first zone to a second program point less than the writeable capacity; and
receive one or more second read commands to read the data from the first zone non-sequentially, wherein a weight of a plurality of updated weights is applied to each of the one or more second read commands, the plurality of updated weights each having a value indicating a level of susceptibility to read errors based on a closeness of the data being read to the second program point, wherein the values of at least two weights of the plurality of updated weights applied to the one or more read second commands are different, wherein the first number of wordlines in the first zone and the second number of wordlines in the first zone each have a first updated weight, and wherein a third number of wordlines in the first zone disposed closest to the second program point has a second updated weight greater than the first updated weight.

6. The storage device of claim 1 , wherein the controller is further configured to close the first zone when a sum of the weights associated with the read commands accumulates to a predetermined value.

7. The storage device of claim 1 , wherein the controller is further configured to:
write data associated with one or more third commands to the first zone sequentially, wherein the one or more third commands fill the first zone to the writeable capacity, and
receive one or more third read commands to read the data from the first zone non-sequentially, wherein a same weight of the plurality of initial weights is applied to each of the one or more third read commands when the first zone is filled to the writeable capacity.

8. A storage device, comprising:
a non-volatile storage unit, wherein a capacity of the non-volatile storage unit is divided into a plurality of zones, and wherein the non-volatile storage unit comprises a plurality of dies, each of the plurality of dies comprising a plurality of erase blocks, and wherein each zone of the plurality of zones comprises a plurality of erase blocks; and
a controller coupled to the non-volatile storage unit, wherein the controller is configured to:
receive a plurality of read commands to read data from a partially full first erase block of a first zone of the plurality of zones non-sequentially, wherein:
a weight of a plurality of weights is applied to each of the one or more read commands, the plurality of weights each having a value indicating a level of susceptibility to read errors based on a location of the data being read within the first erase block,
the values of at least two weights of the plurality of weights applied to the read commands are different,
at least two portions of data of the first zone are associated with two different weights, the at least two portions of data comprising a different number of wordlines, and
a first weight of the plurality of weights having a lowest level of susceptibility of read errors is applied to data read stored closest to a zone starting point of the first zone; and

close the first erase block when a sum of the weights applied to the read commands accumulates to a predetermined value.

9. The storage device of claim 8 , wherein a value of at least four weights of the plurality of weights applied to the one or more read commands are different.

10. The storage device of claim 8 , wherein the data being stored closest to a program point of the partially full first erase block has a higher weight than the data being stored closer to the zone starting point of the partially full first erase block.

11. The storage device of claim 8 , wherein the weight applied to a read command is higher the closer the read command is to a first program point.

12. The storage device of claim 11 , wherein each of the plurality of weights vary between about 0.5 to about 3.

13. The storage device of claim 12 , wherein the predetermined value is about 1000.

14. A storage device, comprising:
a non-volatile storage unit, wherein a capacity of the non-volatile storage unit is divided into a plurality of zones, and wherein the non-volatile storage unit comprises a plurality of dies, each of the plurality of dies comprising a plurality of erase blocks, and wherein each zone of the plurality of zones comprises a plurality of erase blocks; and
a controller coupled to the non-volatile storage unit, wherein the controller is configured to:
receive one or more first read commands to read first data from a first number of wordlines of a partially full first erase block of a first zone, a first weight of a plurality of weights being applied to each of the one or more first read commands, the plurality of weights each having a value indicating a level of susceptibility to read errors;
receive one or more second read commands to read second data from a second number of wordlines of the partially full first erase block, a second weight of the plurality of weights bein

Assignees

• Western Digital Tech Inc

Inventors

• Parker Liam
• Helmick Daniel L

Classifications

• G06F3/0616

  in relation to life time, e.g. increasing Mean Time Between Failures [MTBF] · CPC title

• G06F3/0659 Primary

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

• G06F3/0652

  Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket · CPC title

• G06F3/064

  Management of blocks · CPC title

• G06F3/0679 Primary

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