Hybrid drive writing copy of data to disk when non-volatile semiconductor memory nears end of life
View Patent ↗A hybrid drive is disclosed comprising a head actuated over a disk, and a non-volatile semiconductor memory (NVSM). When a write command is received from a host that is mapped to the NVSM, the write command is serviced by writing data to the NVSM, and when a life remaining of the NVSM falls below a threshold, by also writing a copy of the data 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 first data;
service the write command by:
writing the first data to the NVSM; and
when a life remaining of the NVSM falls below a threshold, writing a first copy of the first data to the disk;
after servicing the write command, receive a first read command from the host; and
service the first read command by:
reading the first data from the NVSM; and
when the first data is unrecoverable from the NVSM, reading the first copy of the first data from the disk.
2. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to determine the life remaining of the NVSM relative to a number of program/erase cycles.
3. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to determine the life remaining of the NVSM relative to at least one of a program time and an erase time.
4. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to determine the life remaining of the NVSM relative to a number of read errors.
5. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to:
receive a second read command from the host; and
service the second read command by:
reading second data from the NVSM; and
when the life remaining of the NVSM falls below the threshold, writing a copy of the second data to the disk.
6. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to:
receive a second read command from the host; and
service the second read command by:
detecting a number of correctable errors when reading second data from the NVSM; and
when the number of correctable errors exceeds a threshold, writing a copy of the second data to the disk.
7. The hybrid drive as recited in claim 1 , wherein when the first data is unrecoverable from the NVSM, the control circuitry is further operable to write a second copy of the first data to the NVSM.
8. The hybrid drive as recited in claim 1 , wherein when the first data is unrecoverable from the NVSM and the NVSM is read only, the control circuitry is further operable to write a second copy of the first data to the disk.
9. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to:
write to a first area of the disk using a first number of error correction code (ECC) symbols;
write to a second area of the disk using a second number of ECC symbols, wherein the second number is greater than the first number; and
write the first copy of the first data to the second area of the disk.
10. 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 first read command from a host;
service the first read command by:
detecting a number of correctable errors when reading first data from the NVSM; and
when the number of correctable errors exceeds a threshold, writing a first copy of the first data to the disk;
receive a second read command from a host; and
service the second read command by:
reading the first data from the NVSM; and
when the first data is unrecoverable from the NVSM, reading the first copy of the first data from the disk.
11. The hybrid drive as recited in claim 10 , wherein when the first data is unrecoverable from the NVSM the control circuitry is further operable to service the second read command by writing a second copy of the first data to the NVSM.
12. The hybrid drive as recited in claim 10 , wherein when the first data is unrecoverable from the NVSM and the NVSM is read only the control circuitry is further operable to service the second read command by writing a second copy of the first data to the disk.
13. The hybrid drive as recited in claim 10 , wherein the control circuitry is further operable to:
write to a first area of the disk using a first number of error correction code (ECC) symbols;
write to a second area of the disk using a second number of ECC symbols, wherein the second number is greater than the first number; and
write the first copy of the first data to the second area of the disk.
14. A method of operating a hybrid drive, the hybrid drive comprising a head actuated over a disk, and a non-volatile semiconductor memory (NVSM), the method comprising:
receiving a write command from a host, the write command comprising first data;
servicing the write command by:
writing the first data to the NVSM; and
when a life remaining of the NVSM falls below a threshold, writing a first copy of the first data to the disk;
after servicing the write command, receiving a first read command from the host; and
servicing the first read command by:
reading the first data from the NVSM; and
when the first data is unrecoverable from the NVSM, reading the first copy of the first data from the disk.
15. The method as recited in claim 14 , further comprising determining the life remaining of the NVSM relative to a number of program/erase cycles.
16. The method as recited in claim 14 , further comprising determining the life remaining of the NVSM relative to at least one of a program time and an erase time.
17. The method as recited in claim 14 , further comprising determining the life remaining of the NVSM relative to a number of read errors.
18. The method as recited in claim 14 , further comprising:
receiving a second read command from the host; and
servicing the second read command by:
reading second data from the NVSM; and
when the life remaining of the NVSM falls below the threshold, writing a copy of the second data to the disk.
19. The method as recited in claim 14 , further comprising:
receiving a second read command from the host; and
servicing the second read command by:
detecting a number of correctable errors when reading second data from the NVSM; and
when the number of correctable errors exceeds a threshold, writing a copy of the second data to the disk.
20. The method as recited in claim 14 , wherein when the first data is unrecoverable from the NVSM, further comprising writing a second copy of the first data to the NVSM.
21. The method as recited in claim 14 , wherein when the first data is unrecoverable from the NVSM and the NVSM is read only, further comprising writing a second copy of the first data to the disk.
22. The method as recited in claim 14 , further comprising:
writing to a first area of the disk using a first number of error correction code (ECC) symbols;
writing to a second area of the disk using a second number of ECC symbols, wherein the second number is greater than the first number; and
writing the first copy of the first data to the second area of the disk.
23. A method of operating a hybrid drive, the hybrid drive comprising a head actuated over a disk, and a non-volatile semiconductor memory (NVSM), the method comprising:
receiving a first read command from a host; and
servicing the first read command by:
detecting a number of correctable errors when reading first data from the NVSM; and
when the number of correctable errors exceeds a threshold, writing a first copy of the first data to the disk;
receiving a second read command from a host; and
servicing the second read command by:
reading the first data from the NVSM; and
when the first data is unrecoverable from the NVSM, reading the first copy of the first data from the disk.
24. The method as recited in claim 23 , wherein when the first data is unrecoverable from the NVSM, further comprising servicing the second read command by writing a second copy of the first data to the NVSM.
25. The method as recited in claim 23 , wherein when the first data is unrecoverable from the NVSM further comprising servicing the second read command by writing a second copy of the first data to the disk.
26. The method as recited in claim 23 , further comprising:
writing to a first area of the disk using a first number of error correction code (ECC) symbols;
writing to a second area of the disk using a second number of ECC symbols, wherein the second number is greater than the first number; and
writing the first copy of the first data to the second area of the disk.