Hitachi, Ltd.

Ryoichi Inada

Ryo Fujita

Takuma Nishimura

Koji Matsuda

Masahiro Shiraishi

Masataka Nishi

Yuzuru Takahashi

A storage device includes a nonvolatile memory, a volatile memory, and a memory controller. The volatile memory includes a free block management table, and a worn block management table. If the number of free blocks is equal to or larger than a threshold value 1, and errors of the number of equal to or larger than a threshold value 2 but smaller than a threshold value 3 are included in the data read from the nonvolatile memory, the memory controller registers the block in the worn block management table as a worn block. If the number of free blocks becomes smaller than the threshold value 1, the memory controller registers the worn block registered in the worn block management table in the free block management table as the free block.

Memory management method, storage device, and computer with the same

Disclosed is a storage device using non-volatile semiconductor memory that achieves high performance and long life for the device. When managing the non-volatile semiconductor memory (), physical blocks are classified into three types: scratch blocks (), data blocks (), and erased blocks (). Data writing from a host device () is performed on the scratch blocks. When the number of empty pages within a scratch block becomes less than a predetermined number or no longer exists, the block is treated thereafter as a data block, and one of the erased blocks is newly assigned as a scratch block. If there are insufficient erased blocks, a block with relatively less valid data is selected from among the data blocks. After copying all valid data included in the block to a scratch block, the block is erased, and thus an erased block is acquired.

Storage device and memory controller

A storage device includes a non-volatile memory, a cache memory and a memory controller. The non-volatile memory stores a logical-to-physical address translation table for managing partitioned data and storage locations thereof. The cache memory stores a data cache and a logical-to-physical address translation table cache which holds a portion of the logical-to-physical address translation table. When the memory controller receives a data read-out request from outside, in the case no empty entry is found in the data cache, among the partitioned data in the data cache, it creates an empty entry to read out the data thereto by evacuating partitioned data of which entries in the logical-to-physical address translation table exist in the logical-to-physical address translation table cache into the non-volatile memory prior to other partitioned data.

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Atsugi, Japan

Ryoichi Inada