Storage apparatus and storage control method
A storage apparatus includes a first storage device and a second storage device, out of logical-physical translation information which associates a logical page and a physical page in the second storage device with each other. Non-compressed logical-physical translation information in the first storage device is assumed to constitute a first tier, compressed logical-physical translation information in the first storage device is assumed to constitute a second tier, and compressed logical-physical translation information in the second storage device is assumed to constitute a third tier. The storage apparatus includes tier management information for managing which logical page is included in logical-physical translation information of which of the first tier, the second tier, and the third tier. When receiving an I/O with respect to the logical page, the storage apparatus retrieves the logical-physical translation information including the logical page for which the I/O has been received, based on the tier management information.
1. A storage apparatus, comprising:
a first storage device;
a second storage device; and
a controller configured to control the first storage device and the second storage device,
in logical-physical translation information which associates logical pages constituting a logical storage area of the second storage device and physical pages constituting a physical storage area of the second storage device with each other,
the logical-physical translation information stored in a non-compressed state in the first storage device belongs to a first tier
the logical-physical translation information stored in a compressed state in the first storage device belongs to a second tier, and
the logical-physical translation information stored in a compressed state in the second storage device belongs to a third tier,
the controller being configured to include tier management information for managing which logical page is included in the logical-physical translation information of which of the first tier, the second tier, and the third tier, and
the controller being configured to, when receiving an I/O (Input/Output) with respect to a logical page, retrieve the logical-physical translation information including information denoting the logical page for which the I/O has been received, based on the tier management information.
2. The storage apparatus according to claim 1 , wherein
the second storage device is configured to have a slower I/O rate and a larger storage capacity than the first storage device.
3. The storage apparatus according to claim 2 , wherein
the controller is configured to,
when retrieving logical-physical translation information including information denoting the logical page for which the I/O has been received based on the tier management information,
preferentially retrieve logical-physical translation information belonging to the first tier over logical-physical translation information belonging to the second tier, and
preferentially retrieve logical-physical translation information belonging to the second tier over logical-physical translation information belonging to the third tier.
4. The storage apparatus according to claim 2 , wherein
the controller is configured to
duplicate logical-physical translation information, out of logical-physical translation information belonging to the third tier, of which an I/O frequency indicating a frequency of I/O to a logical page included in the logical-physical translation information is equal to or higher than a first threshold, to the first storage device in a compressed state, and cause the duplicated logical-physical translation information to belong to the second tier, and
decompress logical-physical translation information, out of logical-physical translation information belonging to the second tier, of which the I/O frequency is equal to or higher than a second threshold, which is higher than the first threshold, to bring the logical-physical translation information into a non-compressed state, and cause the logical-physical translation information to belong to the first tier.
5. The storage apparatus according to claim 4 , wherein
the controller is configured to
delete from the second storage device logical-physical translation information, out of logical-physical translation information belonging to the second tier, of which the I/O frequency is lowest, and
bring logical-physical translation information, out of logical-physical translation information belonging to the first tier, of which the I/O frequency is lowest into a compressed state, and cause the logical-physical translation information to belong to the second tier.
6. The storage apparatus according to claim 5 , wherein
the I/O frequency is a value based on access to the logical page from an external apparatus.
7. The storage apparatus according to claim 2 , wherein
the tier management information includes a storage location in the first storage device, a storage location in the second storage device, and a data size of the logical-physical translation information, relating to the logical-physical translation information, and
the data size is
a data size in a non-compressed state when the logical-physical translation information belongs to the first tier, and
a data size in a compressed state when the logical-physical translation information belongs to the second tier or the third tier.
8. The storage apparatus according to claim 2 , wherein
the controller is configured to
cause logical-physical translation information, of which a priority indicating a degree of priority of the logical-physical translation information is equal to or higher than a first threshold, to belong to the first tier, and
cause logical-physical translation information, of which the priority is equal to or higher than a second threshold and lower than the first threshold, to belong to the second tier.
9. The storage apparatus according to claim 1 , wherein
the second storage device is constituted by a NAND flash memory.
10. A storage control method used in a storage apparatus including a first storage device and a second storage device,
the method comprising:
receiving an I/O with respect to a logical page, and
retrieving logical-physical translation information including information denoting the logical page for which the I/O has been received, based on tier management information,
in regard to the logical-physical translation information which associates logical pages constituting a logical storage area of the second storage device and physical pages constituting a physical storage area of the second storage device with each other,
the logical-physical translation information stored in a non-compressed state in the first storage device to belong to a first tier,
the logical-physical translation information stored in a compressed state in the first storage device to belong to a second tier,
the logical-physical translation information stored in a compressed state in the second storage device to belong to a third tier, and
the tier management information for managing which logical page is included in the logical-physical translation information of which of the first tier, the second tier, and the third tier.