Hybrid drive writing extended error correction code symbols to disk for data sectors stored in non-volatile semiconductor memory
View Patent ↗A hybrid drive is disclosed comprising a head actuated over a disk, and a non-volatile semiconductor memory (NVSM). A write command is received from a host, the write command comprising data. First and second error correction code (ECC) symbols are generated over the data, wherein the second ECC symbols are different than the first ECC symbols. The data and first ECC symbols are written to the NVSM, and the second ECC symbols are written to the disk.
1. A hybrid drive comprising:
a disk;
a head actuated over the disk;
a non-volatile semiconductor memory (NVSM); and
control circuitry operable to:
receive a write command from a host, the write command comprising data;
generate first error correction code (ECC) symbols over the data;
generate second ECC symbols over the data, wherein the second ECC symbols are different than the first ECC symbols;
write the data and first ECC symbols to the NVSM; and
write the second ECC symbols to the disk.
2. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to:
receive a read command from the host to read the data from the NVSM; and
when the data is unrecoverable from the NVSM using the first ECC symbols, recover the data using the second ECC symbols.
3. The hybrid drive as recited in claim 2 , wherein the control circuitry is further operable to verify the recovered data using the first ECC symbols.
4. The hybrid drive as recited in claim 1 , wherein:
the NVSM comprises a plurality of NVSM data sectors;
the disk comprises a plurality of disk data sectors;
each NVSM data sector comprises data and the first ECC symbols; and
the control circuitry is operable to write a plurality of the second ECC symbols generated over the data of a plurality of the NVSM data sectors to a disk data sector.
5. The hybrid drive as recited in claim 4 , wherein the control circuitry is further operable to:
generate third ECC symbols over the second ECC symbols, wherein a number of the second ECC symbols equals a number of the third ECC symbols; and
write the third ECC symbols to the disk data sector.
6. The hybrid drive as recited in claim 5 , wherein the control circuitry is further operable to generate the second and third ECC symbols using the same generator polynomial.
7. The hybrid drive as recited in claim 1 , wherein:
the NVSM comprises a plurality of NVSM data sectors including a first and second NVSM data sector;
each NVSM data sector comprises data and first ECC symbols; and
the second ECC symbols are generated over the data of at least the first and second NVSM data sectors.
8. The hybrid drive as recited in claim 7 , wherein the second ECC symbols are generated by computing a parity over the data of at least the first and second NVSM data sectors.
9. The hybrid drive as recited in claim 7 , wherein the control circuitry is further operable to:
receive a read command from the host to read the first NVSM data sector; and
when the first NVSM data sector is unrecoverable using the first ECC symbols, recover the data of the first NVSM data sector using the second ECC symbols and the second NVSM data sector.
10. The hybrid drive as recited in claim 7 , wherein the control circuitry is further operable to:
write the data recovered for the first NVSM data sector to a third NVSM data sector;
receive a read command from the host to read the second NVSM data sector; and
when the second NVSM data sector is unrecoverable using the first ECC symbols, recover the data of the second NVSM data sector using the second ECC symbols and the third NVSM data sector.
11. The hybrid drive as recited in claim 9 , wherein:
the NVSM comprises a plurality of blocks, wherein each block comprises a plurality of NVSM data sectors and each block is erasable in a unitary operation; and
a first block comprises the first and second NVSM data sectors.
12. The hybrid drive as recited in claim 9 , wherein:
the NVSM comprises a plurality of blocks, wherein each block comprises a plurality of NVSM data sectors and each block is erasable in a unitary operation;
a first block comprises the first NVSM data sector; and
a second block comprises the second NVSM data sector.
13. The hybrid drive as recited in claim 1 , wherein:
the NVSM comprises a plurality of blocks including a first block and a second block, wherein each block comprises a plurality of NVSM data sectors and each block is erasable in a unitary operation;
the first block comprises first and third NVSM data sectors;
the second block comprises second and fourth NVSM data sectors;
the control circuitry is further operable to generate the second ECC symbols over the data of at least the first and third NVSM data sectors; and
the control circuitry is further operable to generate third ECC symbols over the data of at least the second and fourth NVSM data sectors, and write the third ECC symbols to the disk.
14. A method of operating a hybrid drive, the hybrid drive comprising a disk, a head actuated over the disk, and a non-volatile semiconductor memory (NVSM), the method comprising:
receive a write command from a host, the write command comprising data;
generating first error correction code (ECC) symbols over the data;
generating second ECC symbols over the data, wherein the second ECC symbols are different than the first ECC symbols;
writing the data and first ECC symbols to the NVSM; and
writing the second ECC symbols to the disk.
15. The method as recited in claim 14 , further comprising:
receiving a read command from the host to read the data from the NVSM; and
when the data is unrecoverable from the NVSM using the first ECC symbols, recovering the data using the second ECC symbols.
16. The hybrid drive as recited in claim 15 , further comprising verifying the recovered data using the first ECC symbols.
17. The method as recited in claim 14 , wherein:
the NVSM comprises a plurality of NVSM data sectors;
the disk comprises a plurality of disk data sectors;
each NVSM data sector comprises data and the first ECC symbols; and
the method further comprises writing a plurality of the second ECC symbols generated over the data of a plurality of the NVSM data sectors to a disk data sector.
18. The method as recited in claim 17 , further comprising:
generating third ECC symbols over the second ECC symbols, wherein a number of the second ECC symbols equals a number of the third ECC symbols; and
writing the third ECC symbols to the disk data sector.
19. The method as recited in claim 18 , further comprising generating the second and third ECC symbols using the same generator polynomial.
20. The method as recited in claim 14 , wherein:
the NVSM comprises a plurality of NVSM data sectors including a first and second NVSM data sector;
each NVSM data sector comprises data and first ECC symbols; and
the second ECC symbols are generated over the data of at least the first and second NVSM data sectors.
21. The method as recited in claim 20 , wherein the second ECC symbols are generated by computing a parity over the data of at least the first and second NVSM data sectors.
22. The method as recited in claim 20 , further comprising:
receiving a read command from the host to read the first NVSM data sector; and
when the first NVSM data sector is unrecoverable using the first ECC symbols, recovering the data of the first NVSM data sector using the second ECC symbols and the second NVSM data sector.
23. The method as recited in claim 22 , further comprising:
writing the data recovered for the first NVSM data sector to a third NVSM data sector;
receiving a read command from the host to read the second NVSM data sector; and
when the second NVSM data sector is unrecoverable using the first ECC symbols, recovering the data of the second NVSM data sector using the second ECC symbols and the third NVSM data sector.
24. The method as recited in claim 22 , wherein:
the NVSM comprises a plurality of blocks, wherein each block comprises a plurality of NVSM data sectors and each block is erasable in a unitary operation; and
a first block comprises the first and second NVSM data sectors.
25. The method as recited in claim 22 , wherein:
the NVSM comprises a plurality of blocks, wherein each block comprises a plurality of NVSM data sectors and each block is erasable in a unitary operation;
a first block comprises the first NVSM data sector; and
a second block comprises the second NVSM data sector.
26. The method as recited in claim 14 , wherein:
the NVSM comprises a plurality of blocks including a first block and a second block, wherein each block comprises a plurality of NVSM data sectors and each block is erasable in a unitary operation;
the first block comprises first and third NVSM data sectors;
the second block comprises second and fourth NVSM data sectors;
the method further comprises generating the second ECC symbols over the data of at least the first and third NVSM data sectors, and writing the third ECC symbols to the disk; and
the method further comprises generating third ECC symbols over the data of at least the second and fourth NVSM data sectors, and writing the third ECC symbols to the disk.