Semiconductor memory controlling device
According to one embodiment, upon request from an information processor, a semiconductor storage controller writes pieces of data in predetermined units into storage locations in which no data has been written in erased areas within a semiconductor chip's storage area. A third table and a second table which is a subset thereof include physical addresses each indicating a storage location of each of pieces of the data within the semiconductor chip. The first table includes either information specifying a second table entry or information specifying a third table entry. The semiconductor storage controller records the first and the second tables into a volatile memory or records the first table into a volatile memory and the third table into a nonvolatile memory.
1. A semiconductor memory controlling device that writes, into a semiconductor memory chip, host write data requested to be written with a specified logical address used by an information processing apparatus, wherein
the host write data includes one or more pieces of first data in predetermined units,
a physical address is information indicating a storage location of the first data within the semiconductor memory chip,
a first table is stored in a first memory,
a second table is stored in a second memory,
a third table is stored in a third memory which is a nonvolatile memory and includes physical addresses each of which indicates a storage location of each of pieces of the first data within the semiconductor memory chip,
the second table is a subset of the third table and includes the physical addresses each of which indicates the storage location of each of pieces of the first data within the semiconductor memory chip, and
the first table includes either information specifying a second table entry or information specifying a third table entry, and
the semiconductor memory controlling device comprises:
a receiving unit configured to receive the host write data;
a controlling unit configured to write each of the pieces of the first data into a storage location in which no data has been written in a storage region from which data has been erased within a storage region of the semiconductor memory chip; and
a recording unit configured to either record the first table into the first memory and the second table into the second memory, or record the first table into the first memory and the third table into the third memory, wherein
when the controlling unit writes the first data into the semiconductor memory chip, the recording unit records the physical address thereof into a storage region that stores therein the second table, and if a predetermined condition is satisfied, the recording unit records the physical address included in the second table into a storage region that stores therein the third table, the predetermined condition being a condition that a size of a plurality of entries that have been written into the storage region that stores therein the second table is a multiple of a size of the predetermined units.
2. The semiconductor memory controlling device according to claim 1 , wherein if the predetermined condition is satisfied, when the recording unit records the physical address included in the second table into the storage region that stores therein the third table, the recording unit merges the physical address with another physical address that has already been stored in a first storage region that records therein the physical address within the storage region that stores therein the third table so as to record, into the first storage region, the physical addresses that have been merged.
3. The semiconductor memory controlling device according to claim 1 , wherein
the first table includes either first specifying information that specifies each of storage regions that store therein the physical addresses within a storage region that stores therein the second table or second specifying information that specifies each of storage regions that store therein the physical addresses within a storage region that stores therein the third table, and
when the host write data with a first logical address specified by the information processing apparatus is received and the first table already includes the second specifying information, the recording unit records the physical addresses stored in the storage regions specified by the second specifying information into the storage region that stores therein the second table and records the first specifying information that specifies the storage regions that store therein the physical addresses into the storage region that stores therein the first table.
4. The semiconductor memory controlling device according to claim 1 , wherein the recording unit records the physical addresses into the storage region that stores therein the third table by writing the physical addresses into storage locations in which no data has been written in a storage region from which data has been erased within the storage region that stores therein the third table.
5. The semiconductor memory controlling device according to claim 4 , wherein
the first table includes either first specifying information that specifies each of storage regions that store therein the physical addresses within a storage region that stores therein the second table or second specifying information that specifies each of storage regions that store therein the physical addresses within a storage region that stores therein the third table, and
the recording unit further performs garbage collection by writing a second physical address into a new storage region from which data has been erased within the storage region storing therein the third table, the second physical address having been stored in a storage region that is not specified by the second specifying information associated with the information included in the first table.
6. The semiconductor memory controlling device according to claim 1 , wherein the third table is stored in the semiconductor memory chip.