US 2019/0356334 A1Published application

Data storage device employing memory efficient processing of un-converged codewords

AssigneeWestern Digital Technologies, Inc.

InventorsIOURI OBOUKHOV, WELDON M. HANSON, NIRANJAY RAVINDRAN, RICHARD L. GALBRAITH

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Abstract

A data storage device is disclosed comprising a head actuated over a disk comprising a data track having at least a first data segment and a second data segment. A first plurality of codewords are generated, and a first parity sector is generated over the first plurality of codewords. The first plurality of codewords and the first parity sector are written to the first data segment. A second plurality of codewords are generated, and a second parity sector is generated over the second plurality of codewords. The second plurality of codewords and the second parity sector are written to the second data segment. During a read operation the data segments of the data track are processed sequentially to decode the codewords using a low density parity check (LDPC) decoder, wherein the reliability metrics of un-converged codewords are stored in a codeword buffer and updated using the respective parity sector.

Claims15

Dependent claims

A data storage device comprising:

a disk comprising a data track having a plurality of data segments including a first data segment and a second data segment;
a head actuated over the disk;
and
control circuitry configured to:
generate a first plurality of codewords each comprising a plurality of symbols;
generate a first parity sector over the first plurality of codewords;
write the first plurality of codewords and the first parity sector to the first data segment;
generate a second plurality of codewords each comprising a plurality of symbols;
generate a second parity sector over the second plurality of codewords;
write the second plurality of codewords and the second parity sector to the second data segment;
and
during a revolution of the disk:
read the first plurality of codewords and the first parity sector from the first data segment;
process each of the first plurality of codewords read from the first data segment using a Viterbi-type detector, thereby generating codeword reliability metrics;
iteratively process the codeword reliability metrics for each of the first plurality of codewords using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
store the LDPC reliability metrics for each of a plurality of un-converged codewords out of the first plurality of codewords in a codeword buffer;
process the LDPC reliability metrics stored in the codeword buffer using the first parity sector, thereby updating the un-converged codeword reliability metrics;
and
iteratively process the updated codeword reliability metrics for each of the un-converged codewords using the LDPC-type decoder.

16 more elements

A data storage device comprising:

a disk comprising a data track;
a head actuated over the disk;
and
control circuitry configured to:
generate a first plurality of codewords each comprising a plurality of symbols;
generate a second plurality of codewords each comprising a plurality of symbols;
generate a first parity sector over a first plurality of codewords;
generate a second parity sector over the second plurality of codewords;
write the first plurality of codewords and the second plurality of codewords to the data track;
write first parity sector and the second parity sector to the data track;
during a data recover procedure to recover the first plurality of codewords and the second plurality of codewords:
during a first revolution of the disk, read the first plurality of codewords and the first parity sector from the data track;
process each of the first plurality of codewords read from the disk using a Viterbi-type detector, thereby generating codeword reliability metrics;
iteratively process the codeword reliability metrics for each of the first plurality of codewords using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
store the LDPC reliability metrics for each of a plurality of un-converged codewords out of the first plurality of codewords in a codeword buffer;
process the LDPC reliability metrics stored in the codeword buffer using the first parity sector, thereby updating the un-converged codeword reliability metrics out of the first plurality of codewords;
iteratively process the updated codeword reliability metrics for each of the un-converged codewords out of the first plurality of codewords using the LDPC-type decoder;
during a second revolution of the disk following the first revolution of the disk, read the second plurality of codewords and the second parity sector from the data track;
process each of the second plurality of codewords read from the disk using the Viterbi-type detector, thereby generating codeword reliability metrics;
iteratively process the codeword reliability metrics for each of the second plurality of codewords using the LDPC-type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
store the LDPC reliability metrics for each of a plurality of un-converged codewords out of the second plurality of codewords in a codeword buffer;
process the LDPC reliability metrics stored in the codeword buffer using the second parity sector, thereby updating the un-converged codeword reliability metrics out of the second plurality of codewords;
and
iteratively process the updated codeword reliability metrics for each of the un-converged codewords out of the second plurality of codewords using the LDPC-type decoder.

21 more elements

A method of operating a data storage device, the method comprising:

generating a first plurality of codewords each comprising a plurality of symbols;
generating a first parity sector over the first plurality of codewords;
writing the first plurality of codewords and the first parity sector to a first data segment of a data track on a disk;
generating a second plurality of codewords each comprising a plurality of symbols;
generating a second parity sector over the second plurality of codewords;
writing the second plurality of codewords and the second parity sector to a second data segment of the data track;
and
during a revolution of the disk:
reading the first plurality of codewords and the first parity sector from the first data segment;
processing each of the first plurality of codewords read from the first data segment, thereby generating codeword reliability metrics;
iteratively processing the codeword reliability metrics for each of the first plurality of codewords using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
processing the LDPC reliability metrics of a first un-converged codeword out of the first plurality of codewords using the first parity sector, thereby updating the codeword reliability metrics for the first un-converged codeword;
and
iteratively processing the updated codeword reliability metrics for the first un-converged codeword using the LDPC-type decoder.

11 more elements

A method of operating a data storage device, the method comprising:

generating a first plurality of codewords each comprising a plurality of symbols;
generating a second plurality of codewords each comprising a plurality of symbols;
generating a first parity sector over a first plurality of codewords;
generating a second parity sector over the second plurality of codewords;
writing the first plurality of codewords and the second plurality of codewords to a data track on a disk;
writing first parity sector and the second parity sector to the data track;
during a data recover procedure to recover the first plurality of codewords and the second plurality of codewords:
during a first revolution of the disk, reading the first plurality of codewords and the first parity sector from the data track;
processing each of the first plurality of codewords read from the disk, thereby generating codeword reliability metrics;
iteratively processing the codeword reliability metrics for each of the first plurality of codewords using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
processing the LDPC reliability metrics of a first un-converged codeword out of the first plurality of codewords using the first parity sector, thereby updating the codeword reliability metrics for the first un-converged codeword;
iteratively processing the updated codeword reliability metrics for the first un-converged codeword using the LDPC-type decoder;
during a second revolution of the disk following the first revolution of the disk, reading the second plurality of codewords and the second parity sector from the data track;
processing each of the second plurality of codewords read from the disk, thereby generating codeword reliability metrics;
iteratively processing the codeword reliability metrics for each of the second plurality of codewords using the LDPC-type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
processing the LDPC reliability metrics of a second un-converged codeword out of the second plurality of codewords using the second parity sector, thereby updating the codeword reliability metrics for the second un-converged codeword;
and
iteratively processing the updated codeword reliability metrics for the second un-converged codeword using the LDPC-type decoder.

15 more elements

Control circuitry configured to:

generate a first plurality of codewords each comprising a plurality of symbols;
generate a first parity sector over the first plurality of codewords;
write the first plurality of codewords and the first parity sector to a first data segment of a data track on a disk;
generate a second plurality of codewords each comprising a plurality of symbols;
generate a second parity sector over the second plurality of codewords;
write the second plurality of codewords and the second parity sector to a second data segment of the data track;
and
during a revolution of the disk:
read the first plurality of codewords and the first parity sector from the first data segment;
process each of the first plurality of codewords read from the first data segment using a Viterbi-type detector, thereby generating codeword reliability metrics;
iteratively process the codeword reliability metrics for each of the first plurality of codewords using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
store the LDPC reliability metrics for each of a plurality of un-converged codewords out of the first plurality of codewords in a codeword buffer;
process the LDPC reliability metrics stored in the codeword buffer using the first parity sector, thereby updating the un-converged codeword reliability metrics;
and
iteratively process the updated codeword reliability metrics for each of the un-converged codewords using the LDPC-type decoder.

12 more elements

Control circuitry configured to:

generate a first plurality of codewords each comprising a plurality of symbols;
generate a second plurality of codewords each comprising a plurality of symbols;
generate a first parity sector over a first plurality of codewords;
generate a second parity sector over the second plurality of codewords;
write the first plurality of codewords and the second plurality of codewords to a data track on a disk;
write first parity sector and the second parity sector to the data track;
during a data recover procedure to recover the first plurality of codewords and the second plurality of codewords:
during a first revolution of the disk, read the first plurality of codewords and the first parity sector from the data track;
process each of the first plurality of codewords read from the disk using a Viterbi-type detector, thereby generating codeword reliability metrics;
iteratively process the codeword reliability metrics for each of the first plurality of codewords using a low density parity check (LDPC) type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
store the LDPC reliability metrics for each of a plurality of un-converged codewords out of the first plurality of codewords in a codeword buffer;
process the LDPC reliability metrics stored in the codeword buffer using the first parity sector, thereby updating the un-converged codeword reliability metrics out of the first plurality of codewords;
iteratively process the updated codeword reliability metrics for each of the un-converged codewords out of the first plurality of codewords using the LDPC-type decoder;
during a second revolution of the disk following the first revolution of the disk, read the second plurality of codewords and the second parity sector from the data track;
process each of the second plurality of codewords read from the disk using the Viterbi-type detector, thereby generating codeword reliability metrics;
iteratively process the codeword reliability metrics for each of the second plurality of codewords using the LDPC-type decoder, thereby generating a LDPC reliability metric for each symbol of each codeword;
store the LDPC reliability metrics for each of a plurality of un-converged codewords out of the second plurality of codewords in a codeword buffer;
process the LDPC reliability metrics stored in the codeword buffer using the second parity sector, thereby updating the un-converged codeword reliability metrics out of the second plurality of codewords;
and
iteratively process the updated codeword reliability metrics for each of the un-converged codewords out of the second plurality of codewords using the LDPC-type decoder.

17 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/983,033Filed 17 May 2018
Published: 21 Nov 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

H03M 13/1128
Decoding: judging correct decoding and iterative stopping criteria other than syndrome check and upper limit for decoding iterations
G06F 3/0619
Improving the reliability of storage systems: in relation to data integrity, e.g. data losses, bit errors
G06F 3/064
Organizing or formatting or addressing of data: management of blocks
G06F 3/0656
Vertical data movement, i.e. input-output transfer; data movement between one or more hosts and one or more storage devices: data buffering…

Family

US 10,530,390 B2Related patent
US 2019/0356334 A1This patent

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