Storage system having plurality of flash packages

• US 8,484,414 B2
• Filed: 08/31/2009
• Issued: 07/09/2013
• Est. Priority Date: 08/31/2009
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sugimoto, Sadahiro, Yamamoto, Akira, Yamamoto, Masayuki, Araki, Akihiko
• Primary Examiner(s): Dudek, Jr., Edward
• Assistant Examiner(s): Rossiter, Sean D
• Application Number:
  US12/664,721
• Publication Number:
  US 20110231594A1
• Time in Patent Office: 1,408 Days
• Field of Search: None
• US Class Current: 711/114
• CPC Class Codes: G06F 11/108 Parity data distribution in semiconductor storages, e.g. in SSD
• CPC Class Codes: G06F 2211/1035 Keeping track, i.e. keeping track of data and parity changes
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0688 Non-volatile semiconductor memory arrays
• CPC Class Codes: G11C 16/3495 Circuits or methods to detect or delay wearout of nonvolatile EPROM or EEPROM memory devices, e.g. by counting numbers of erase or reprogram cycles, by using multiple memory areas serially or cyclically

Abstract

The storage system comprises a plurality of flash packages configuring one or more RAID groups, and a controller coupled to the plurality of flash packages. Each flash package comprises a plurality of flash chips configured from a plurality of physical blocks. The controller identifies a target area related to an unnecessary area, unmaps a physical block allocated to a logical block belonging to this target area from this logical block, and manages the unmapped physical block as a free block.

Claims

1. A storage system comprising:

a plurality of first flash memory drives configuring a first RAID group and a plurality of second flash memory drives configuring a second RAID group; and

a storage controller coupled to a host computer and the first and the second drives;

wherein each of the first and the second flash memory drives includes a drive controller and a storage area, the storage area comprising a plurality of physical blocks, each of the physical blocks comprising a plurality of pages, the drive controller allocating a part of the physical blocks to a plurality of logical blocks provided by the drive controller, managing an unallocated part of the physical blocks as free blocks, executing a read or write process to respective pages of the allocated physical blocks, erasing all of the pages of one of the physical blocks when the one of the physical blocks is unmapped from the logical block, and;

wherein the storage controller provides to the host computer, a logical unit configured by a plurality of logical chunks, manages a plurality of physical chunks, each of the physical chunks configured by ones of the logical blocks of either one of the first or the second RAID groups, and allocates one of the physical chunks to one of the logical chunks in response to a write operation addressed within the one of the logical chunks;

wherein if a write error has occurred in a write operation addressed in a first one of the physical chunks configured by the ones of the logical blocks of the first RAID group due to a shortage of free blocks in one or more of the first flash memory drives, the storage controller is configured to migrate data from the first one of the physical chunks to a second one of the physical chunks configured by ones of the logical blocks of the second RAID group, allocate the second one of the physical chunks to one of the logical chunks where the first one of the physical chunks has been allocated and send an instruction to unmap the first one of the physical chunks to the first flash memory drives, and

wherein each of the drive controllers of the first flash memory drives receiving the instruction to unmap the first one of the physical chunks are configured to unmap the respective storage area corresponding to the logical blocks configuring the first one of the physical chunks.

2. The storage system according to claim 1, comprising:

wherein the storage controller is configured to deallocate a third physical chunk from one of the logical chunks, and send an instruction to unmap the third physical chunk to the drives, and

wherein the drive controllers which received the instruction is configured to unmap storage area corresponding to logical blocks configuring the third physical chunk.

3. The storage system according to claim 1, comprising:

wherein the storage controller is configured to delete the logical unit, send an instruction to unmap all the physical chunks allocated to the logical unit to the drives, and

wherein the drive controllers which received the instruction is configured to unmap storage area corresponding to logical blocks configuring the physical chunks allocated to the logical unit.