Data storage device and method for non-balanced mapping for variable read resolution
Data is often stored in a multi-level memory (e.g., a quad-level cell (QLC)) using a mapping that balances the bit error rate among the various pages in the memory. The number of sense operations needed to read each page is also relatively balanced. The data storage device presented herein can decide to store data using a non-balanced mapping if there is a desire to later read a low-resolution version of the data. With a non-balanced mapping, fewer sense operations are needed to read the lower page of data, which contains the low-resolution version of the data. Other pages can be read if a higher-resolution version of the data is desired, and techniques can be used to mitigate the higher bit error rate that may be encountered in those other pages because of use of the non-balanced mapping.
1 . A data storage device comprising:
a memory comprising multi-level memory cells; and
one or more processors, individually or in combination, configured to:
determine whether there is a need for providing a low-resolution version of data;
in response to determining that there is not a need for providing a low-resolution version of the data, store the data in the memory using a first mapping; and
in response to determining that there is a need for providing a low-resolution version of the data, store the data in the memory using a second mapping, wherein reading only a lower page of the data provides the low-resolution version of the data, and wherein fewer memory sense operations are needed to read the lower page when the data is stored using the second mapping than when the data is stored using the first mapping.
2 . The data storage device of claim 1 , wherein the first mapping comprises a 4-4-3-4 mapping and the second mapping comprises a 1-2-4-8 mapping.
3 . The data storage device of claim 1 , wherein the first mapping comprises a bit error rate (BER) balanced mapping and the second mapping comprises a non-BER-balanced mapping.
4 . The data storage device of claim 1 , wherein the determining is performed in response to the data being received from a host.
5 . The data storage device of claim 1 , wherein the determining is performed in response to re-mapping the data, which was previously stored in the memory using a different mapping.
6 . The data storage device of claim 1 , wherein most-significant bits of the data are stored in the lower page.
7 . The data storage device of claim 1 , wherein the low-resolution version of the data comprises a low-resolution version of a parameter of a machine learning model.
8 . The data storage device of claim 1 , wherein the low-resolution version of the data comprises a low-resolution version of an image.
9 . The data storage device of claim 1 , wherein the memory comprises a three-dimensional memory.
10 . In a data storage device comprising multi-level memory cells, a method comprising:
determining whether data is designated for reading with dynamic read resolution; and
in response to determining that the data is designated for reading with dynamic read resolution, storing the data in the memory using a non-BER (bit-error-rate) balanced mapping, wherein fewer memory sense operations are needed to read page(s) of the data for a low-resolution read when the data is stored using the non-BER-balanced mapping instead of a BER-balanced mapping.
11 . The method of claim 10 , further comprising:
performing an operation to mitigate non-balanced BER caused by using the non-BER-balanced mapping.
12 . The method of claim 11 , further comprising:
reading a higher-resolution of the data by reading more pages of the data from the memory.
13 . The method of claim 10 , wherein the data comprises an image.
14 . The method of claim 10 , wherein the data comprises a parameter of a machine-learning model.
15 . The method of claim 10 , wherein the determining is performed in response to the data being received from a host.
16 . The method of claim 10 , wherein the determining is performed in response re-mapping the data, which was previously stored in the memory using a different mapping.
17 . The method of claim 10 , wherein the data is explicitly designated for reading with dynamic read resolution by a host.
18 . The method of claim 10 , wherein the data is implicitly designated for reading with dynamic read resolution by a host.
19 . The method of claim 10 , wherein the BER balanced mapping comprises a 4-4-3-4 mapping and the non-BER balanced mapping comprises a 1-2-4-8 mapping.
20 . A data storage device comprising:
a memory comprising multi-level memory cells; and
means for:
selecting a mapping from a plurality of mappings based on whether the data is designated for variable read resolution; and
writing the data in the memory using the selected mapping.