21-06-2012, 02:09 PM
Flash Memory
Flash Memory.pdf (Size: 575.7 KB / Downloads: 35)
Abstract:
Flash memory has continuously been dominating on HDD for performance oriented modern applications by last more than two decades. The existence of mechanical parts in the working of a HDD causes a hindrance in their performance. The reading/writing speeds are often limited by the rotational speeds of the disk in the HDD. They are also poorly resistant to mechanical shocks, resulting in damage. SSDs, on the other hand retain data in non-volatile memory chips and contain no moving parts. Compared to electromechanical HDDs, SSDs are typically more resistant to physical shocks, are silent, have lower access time and latency, but are more expensive. Currently the high capacity MLC flash SSDs are becoming center of attraction for large size multimedia systems to support their increasing storage and throughput demands. The advantage of MLC flash over SLC flash is lower cost, higher capacity and increased throughput. However, MLC flash SSDs suffer for lesser data reliability, higher bit error ratio and reduced erasure cycle. In this report, the working of HDD and flash NAND SSD are explained and their performances are compared.
Data Storage Devices :
A data storage device is a device for recording information (data). A storage device may hold information, process information, or both. A device that only holds information is a recording medium. Devices that process information (data storage equipment) may either access a separate portable (removable) recording medium or a permanent component to store and retrieve information.
Hard Disk Drives :
[2] A hard disk drive (HDD) is a device for storing and retrieving data in digital form. It consists of one or more rigid, rapidly rotating discs (platters), which are coated with magnetic material and provided with magnetic heads to read and write data from the surfaces. Hard drives have the following features:
Working :
A hard disk drive basically stores data by magnetizing a thin film of ferromagnetic material on a disk. The user data is usually encoded into a run-length limited code and the encoded data is embedded as a pattern of sequential magnetic transitions on the disk. The data is represented by the time between transitions. The data is read from the disk by detecting the transitions and then decoding the written run-length limited data back to the user data.
Solid State Drives :
[2][3] A solid-state drive (SSD), also called solid-state disk, is a data storage device that uses solid-state memory to store data. SSDs are distinguished from traditional magnetic disks such as hard disk drives (HDDs) or floppy disk, which are electromechanical devices containing spinning disks and movable read/write heads. In contrast, SSDs use semiconductor memories that retain data in non-volatile memory chips and contain no moving parts. Compared to electromechanical HDDs, SSDs are typically less susceptible to physical shock, are silent, have lower access time and latency, but are more expensive per gigabyte (GB). SSDs use the same interface as hard disk drives, thus easily replacing them in most applications.
Flash Memory.pdf (Size: 575.7 KB / Downloads: 35)
Abstract:
Flash memory has continuously been dominating on HDD for performance oriented modern applications by last more than two decades. The existence of mechanical parts in the working of a HDD causes a hindrance in their performance. The reading/writing speeds are often limited by the rotational speeds of the disk in the HDD. They are also poorly resistant to mechanical shocks, resulting in damage. SSDs, on the other hand retain data in non-volatile memory chips and contain no moving parts. Compared to electromechanical HDDs, SSDs are typically more resistant to physical shocks, are silent, have lower access time and latency, but are more expensive. Currently the high capacity MLC flash SSDs are becoming center of attraction for large size multimedia systems to support their increasing storage and throughput demands. The advantage of MLC flash over SLC flash is lower cost, higher capacity and increased throughput. However, MLC flash SSDs suffer for lesser data reliability, higher bit error ratio and reduced erasure cycle. In this report, the working of HDD and flash NAND SSD are explained and their performances are compared.
Data Storage Devices :
A data storage device is a device for recording information (data). A storage device may hold information, process information, or both. A device that only holds information is a recording medium. Devices that process information (data storage equipment) may either access a separate portable (removable) recording medium or a permanent component to store and retrieve information.
Hard Disk Drives :
[2] A hard disk drive (HDD) is a device for storing and retrieving data in digital form. It consists of one or more rigid, rapidly rotating discs (platters), which are coated with magnetic material and provided with magnetic heads to read and write data from the surfaces. Hard drives have the following features:
Working :
A hard disk drive basically stores data by magnetizing a thin film of ferromagnetic material on a disk. The user data is usually encoded into a run-length limited code and the encoded data is embedded as a pattern of sequential magnetic transitions on the disk. The data is represented by the time between transitions. The data is read from the disk by detecting the transitions and then decoding the written run-length limited data back to the user data.
Solid State Drives :
[2][3] A solid-state drive (SSD), also called solid-state disk, is a data storage device that uses solid-state memory to store data. SSDs are distinguished from traditional magnetic disks such as hard disk drives (HDDs) or floppy disk, which are electromechanical devices containing spinning disks and movable read/write heads. In contrast, SSDs use semiconductor memories that retain data in non-volatile memory chips and contain no moving parts. Compared to electromechanical HDDs, SSDs are typically less susceptible to physical shock, are silent, have lower access time and latency, but are more expensive per gigabyte (GB). SSDs use the same interface as hard disk drives, thus easily replacing them in most applications.