SSD(Solid state drive )

SUBMITTED BY

KARTHIK M

M.SC. COMPUTER SCIENCE

ZHAPMCS004

Introduction

•SSD can be thought of as an oversized and more sophisticated version of the humble USB memory stick.

• SSDs can be used in place of hard disk drives (HDDs).

•Like a memory stick, there are no moving parts to an SSD.

•Information is stored in microchips

•A typical SSD uses what is called NAND based flash memory.

FLASH MEMORY

There are two types of flash memory, NAND and NOR. The names refer to the type of logic gate used in each memory cell.

Flash memory (both NOR and NAND types) was invented by Fujio Masuoka while working for Toshiba

NAND is a non volatile memory were as NOR is a volatile memory

NOR based memory is faster than NAND based memory

SSD make use of NAND based flash memory to store data

External view of SSD

Internal view of SSD

Architecture of SSD

Main component are :1) Several NAND based flash storage 2) Controller chip

NAND Storage

In flash memory, each memory cell resembles a standard MOSFET transistor but with an extra gate called floating gate .

Floating gate help to hold the charge for a long time

Types of NAND

Types of NAND used in SSD determines the characteristic of SSD .

Three popular NAND used in SSD are :

SLC NAND(single level cell)

MLC NAND(multi level cell)

TLC NAND(three level cell)

This three types of NAND can be used for building the FLASH storage in SSD

Single Level Cell NAND

This type of NAND can store single bit per cell

The characteristic of SLC are:

Highest performance, enterprise grade NAND

Up to 100,000 program/erase cycles per cell (highest endurance)

Lowest density (1 bit per cell, lower is better for endurance)

Lower power consumption

Faster write speeds

Much higher cost (3 times higher than MLC)

Good fit for industrial grade devices, critical applications

Multi Level cell NAND

This type of NAND can store two bit per cell. This type of SSD are commonly used

The characteristic of MLC are:

Average performance, consumer grade NAND

Up to10,000 program/erase cycles per cell

Higher density (2 or more bits per cell)

Lower endurance limit than SLC

Lower cost (3 times lower than SLC)

Good fit for consumer products.

THREE Level cell NAND

This type of NAND can store three bit per cell. This type of SSD are rarely used .

The characteristic of TLC are:

Lower performance

Up to 5,000 program/erase cycles per cell

Highest density (3 bits per cell)

Lower endurance limit than MLC and SLC

Best price point (30% lower than MLC)

Somewhat slower read and write speed than MLC

Good fit for lower-end consumer products.

HOW A SINGLE CELL STORE MORE DATA

SLC :

MLC :

A single cell can store more than one bit by varying the amount of voltage stored.The above figure shows how an SLC cell Defer from MLC

Flash memory controller

A flash memory controller (or flash controller) manages the data stored on flash memory and communicates with a computer or electronic device

Flash controller perform following tasks

Wear leveling.

Background Garbage collection.

Defect Management.

Host Interface.

error correction

HDD vs SDDCOMPARISON FACTORS HDD SSD

SPEED HDD has higher latency, longer read/write times, and supports fewer IOPs

SSD has lower latency, faster read/writes, and supports more IOPs

Heat, Electricity, Noise Hard disk drives use more electricity to rotate the platters, generating heat and noise.

Since no such rotation is needed in solid state drives, they use less power and noise.

Defragmentation The performance of HDD drives worsens due to fragmentation so defragmented required

SSD drive performance is not impacted by fragmentation. So defragmentation is not necessary.

Weight HDDs are heavier than SSD drives SSD are lighter because they do not have the rotating disks, spindle and motor.

Price Low price when compared to SSD High price

Data Transfer in an SSD vs. HDD

HDD

In an HDD, data transfer is sequential.

In HDD the physical read/write head "seeks" an appropriate point in the hard drive to execute the operation. This seek time can be significant.

SDD

Data transfer is not sequential, it is random access so it is faster.

There is consistent read performance because the physical location of data is irrelevant

SSDs have no read/write heads and thus no delays due to head motion (seeking).

APPLICATION OF SSD

SSDs were mainly used in those, where the speed of the storage system needed to be as fast as possible.

Organizations that can benefit from faster access of system data include equity trading companies, telecommunication corporations, and video streaming.

SSD are used as cache at server side of Enterprises.

Storing the operating system in SSD can improve the boot up speed and overall performance of a Laptop or Desktop

By storing the games in SSD , the loading time of games can be reduced

Disadvantage of SSD

The most noticeable disadvantage of SSDs is limited storage capacity compared to traditional hard drives .

SSDs have high price per GB.

If SSD is damaged it is nearly impossible to recover the data, but HDD's magnetic disk may be safe even hard drive is damaged.

Till now lifetime of SSD is not so much long.

Future of SSD

Future of SSD depend upon the development of 3D NAND

This figure shows a basic idea of 3D NAND technology

Conclusion

SSD is the best alternative technology for hard disk available in the market.

A hard can never match the performance of an SSD even its spin at 7200 rpm

Most of the problem SSD faced will be solved in near future and hard disk will be completely replaced by SSD

Thank you