Hybrid drive executing biased migration policy during host boot to migrate data to a non-volatile semiconductor memory
View Patent ↗A hybrid drive is disclosed comprising a head actuated over a disk comprising a plurality of data sectors, and a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments. A logical block address (LBA) is mapped to a data sector on the disk. During a bias interval following the start of a host boot operation, a biased migration policy is executed that increases a likelihood of migrating the LBA to the NVSM. After the bias interval a normal migration policy is executed.
1. A hybrid drive comprising:
a disk comprising a plurality of data sectors;
a head actuated over the disk;
a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments; and
control circuitry operable to:
map a logical block address (LBA) to a data sector on the disk;
detect a start of a host boot operation;
execute a biased migration policy during a bias interval following the start of the boot operation, wherein the biased migration policy increases a likelihood of migrating the LBA to the NVSM;
execute a normal migration policy after the bias interval;
migrate the LBA to the NVSM in response to the normal and biased migration policies by:
copying data stored in the data sector to a memory segment in the NVSM; and
mapping the LBA to the memory segment in the NVSM;
maintain a read counter for the LBA; and
bias the migration of the LBA to the NVSM during the bias interval based on the read counter.
2. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to:
adjust the read counter by a first value each time the LBA is read during the bias interval;
adjust the read counter by a second value each time the LBA is read after the bias interval; and
migrate the LBA to the NVSM by comparing the read counter to a threshold.
3. The hybrid drive as recited in claim 2 , wherein the control circuitry is further operable to adjust the first value as a function of a number of access commands executed after the start of the host boot operation.
4. The hybrid drive as recited in claim 3 , wherein the control circuitry is further operable to reduce the first value as the number of access commands increases.
5. The hybrid drive as recited in claim 2 , wherein the control circuitry is further operable to reset the read counter at the start of the host boot operation.
6. The hybrid drive as recited in claim 2 , wherein the first value is based on a value of the read counter at the start of the host boot operation.
7. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to:
migrate the LBA to the NVSM by comparing the read counter to a threshold, wherein the threshold is adjusted during the bias interval.
8. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to detect the start of the host boot operation when a command to read a master boot record is received from the host.
9. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to detect the start of the host boot operation after completing a power on reset.
10. The hybrid drive as recited in claim 1 , wherein the bias interval comprises a predetermined number of access commands received from the host after the start of the host boot operation.
11. The hybrid drive as recited in claim 1 , wherein the bias interval comprises a predetermined time interval after the start of the host boot operation.
12. The hybrid drive as recited in claim 1 , wherein the control circuitry is further operable to migrate the LBA to the NVSM in response to a ratio of the read counter to a number of read commands received from the host.
13. The hybrid drive as recited in claim 12 , wherein the control circuitry is further operable to:
maintain a write counter for the LBA; and
migrate the LBA to the NVSM in response to a ratio of the write counter to the read counter.
14. A method of operating a hybrid drive comprising a head actuated over a disk comprising a plurality of data sectors, and a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments, the method comprising:
mapping a logical block address (LBA) to a data sector on the disk;
detecting a start of a host boot operation;
executing a biased migration policy during a bias interval following the start of the boot operation, wherein the biased migration policy increases a likelihood of migrating the LBA to the NVSM;
executing a normal migration policy after the bias interval;
migrating the LBA to the NVSM in response to the normal and biased migration policies by:
copying data stored in the data sector to a memory segment in the NVSM; and
mapping the LBA to the memory segment in the NVSM;
maintaining a read counter for the LBA; and
biasing the migration of the LBA to the NVSM during the bias interval based on the read counter.
15. The method as recited in claim 14 , further comprising:
adjusting the read counter by a first value each time the LBA is read during the bias interval;
adjusting the read counter by a second value each time the LBA is read after the bias interval; and
migrating the LBA to the NVSM by comparing the read counter to a threshold.
16. The method as recited in claim 15 , further comprising adjusting the first value as a function of a number of access commands executed after the start of the host boot operation.
17. The method as recited in claim 16 , further comprising reducing the first value as the number of access commands increases.
18. The method as recited in claim 15 , further comprising resetting the read counter at the start of the host boot operation.
19. The method as recited in claim 15 , wherein the first value is based on a value of the read counter at the start of the host boot operation.
20. The method as recited in claim 14 , further comprising:
migrating the LBA to the NVSM by comparing the read counter to a threshold, wherein the threshold is adjusted during the bias interval.
21. The method as recited in claim 14 , further comprising detecting the start of the host boot operation when a command to read a master boot record is received from the host.
22. The method as recited in claim 14 , further comprising detecting the start of the host boot operation after completing a power on reset.
23. The method as recited in claim 14 , wherein the bias interval comprises a predetermined number of access commands received from the host after the start of the host boot operation.
24. The method as recited in claim 14 , wherein the bias interval comprises a predetermined time interval after the start of the host boot operation.
25. The method as recited in claim 14 , further comprising migrating the LBA to the NVSM in response to a ratio of the read counter to a number of read commands received from the host.
26. The method as recited in claim 25 , further comprising:
maintaining a write counter for the LBA; and
migrating the LBA to the NVSM in response to a ratio of the write counter to the read counter.
27. A hybrid drive comprising:
a disk comprising a plurality of data sectors;
a head actuated over the disk;
a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments; and
control circuitry operable to:
map a logical block address (LBA) to a data sector on the disk;
detect a start of a host boot operation;
execute a first migration policy during a bias interval following the start of the boot operation, wherein the first migration policy increases a likelihood of migrating the LBA to the NVSM;
execute a second migration policy after the bias interval, wherein the second migration policy does not increase a likelihood of migrating the LBA to the NVSM;
migrate the LBA to the NVSM in response to the normal and biased migration policies by:
copying data stored in the data sector to a memory segment in the NVSM; and
mapping the LBA to the memory segment in the NVSM;
maintain a read counter for the LBA; and
bias the migration of the LBA to the NVSM during the bias interval based on the read counter.
28. A method of operating a hybrid drive comprising a head actuated over a disk comprising a plurality of data sectors, and a non-volatile semiconductor memory (NVSM) comprising a plurality of memory segments, the method comprising:
mapping a logical block address (LBA) to a data sector on the disk;
detecting a start of a host boot operation;
executing a first migration policy during a bias interval following the start of the boot operation, wherein the biased migration policy increases a likelihood of migrating the LBA to the NVSM;
executing a second migration policy after the bias interval, wherein the second migration policy does not increase a likelihood of migrating the LBA to the NVSM;
migrating the LBA to the NVSM in response to the normal and biased migration policies by:
copying data stored in the data sector to a memory segment in the NVSM; and
mapping the LBA to the memory segment in the NVSM;
maintaining a read counter for the LBA; and
biasing the migration of the LBA to the NVSM during the bias interval based on the read counter.