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Method and System for Reducing Performance Impact of Solid-state Drive Garbage Collection in a Mirrored Environment Using Internal Stats

IP.com Disclosure Number: IPCOM000245733D
Publication Date: 2016-Apr-04
Document File: 3 page(s) / 67K

Publishing Venue

The IP.com Prior Art Database

Abstract

A method and system is disclosed for reducing the performance impact of solid-state drive (SSD) garbage collection in a mirrored environment by using a number of free blocks available on an SSD in order to prefer read operations to. The method and system uses the number of free blocks to determine an SSD to which a Redundant Array of Inexpensive Disks (RAID) controller will prefer read operations to, thereby decreasing performance issues caused by garbage collection.

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Method and System for Reducing Performance Impact of Solid-state Drive Garbage Collection in a Mirrored Environment Using Internal Stats

Garbage collection is an automatic process of taking "dirty" blocks of flash memory and rendering the dirty pieces writable again. The dirty blocks of the flash memory that have been written and can no longer be written to must be erased so that the flash memory can be re-written to. A solid-state drive (SSD) controller detects when garbage collection is necessary and takes a block of flash memory containing clean as well as dirty flash pages, and erases the whole block clean, moving the clean data to another location. This occurs because the smaller pages situated inside each block of data cannot be erased individually and all erasures must happen per block. Firstly, the SSD controller reads the data on the block, copies the good data to another block and then erases the dirty data on the block that the data was stored on.

All of this reading and writing of data involved in the garbage collection has a negative effect on performance. Therefore, a method and system is required for reducing the performance impact of SSD garbage collection in a mirrored environment.

Disclosed is a method and system for reducing the performance impact of SSD garbage collection in a mirrored environment by using a number of free blocks available on an SSD in order to prefer read operations to. The method and system uses the number of free blocks to determine an SSD to which a Redundant Array of Inexpensive Disks (RAID) controller will prefer read operations to, thereby decreasing performance issues caused by garbage collection.

In an embodiment, the method and system reduces a performance drain from garbage collection on flash memory in mirrored systems by limiting read operations based on a comparison of two SSDs and an amount of free blocks contained in each of the two SSDs. An SSD that contains a highest amount of free blocks is marked as "preferred," so that a majority of read operations is performed on the SSD which is farther away from garbage collection. However, the read operations happen from both the SSDs but with a preference for one SSD over the other. Thus, most of the read operations happen on one SSD rather than on both the SSDs.

Further, when the method and system uses two mirrored SSDs where the same write operations are happening in the

two mirrored SSDs simultaneously, the read operations happening on the SSD are limited with the least free blocks, in favor of having most of the read operations done on the SSD with a highest number of free blocks.

In order to i...