Different Types of Storage Devices

Submitted By: Deelip Khanal

www.deelipk.com

ReferencesStoragereview.com

Wikipedia.org

About.com

Introduction to Computers(Peter Nortons)

Helium.com

Magnetic TapeIntroduction:

• Magnetic tape has been used for data storage for over 50 years. Magnetic tapes are available in the form of different formulations and packaging which we widely know as magnetic storage device in general.

• Magnetic tape as its name says consists of magnetic coating. A narrow plastic strip is coated lightly by magnets which is the foundation of magnetic Tape.

• It is used for audio recording, video recording as well as computer data

storage.

Magnetic Tape was first developed in Germany which revolutionized the broadcasting and recording industry.

The recorded radio and television program broadcasting made possible only after the invention of magnetic tape. Before that radio and television broadcasting used to be all live because of there was no medium to record a program to show later.

Before magnetic tape, gramophones were used for recording but they were recorded in one take. Magnetic tape made it possible for the recordings to be created in multiple stages and easily mixed.

History & Early Use

Use in Computer Storage•The use of magnetic tape for computer data storage has been one of the constants of the computer industry. In all formats, a tape drive uses precisely-controlled motors to wind the tape from one reel to another, passing a tape head as it does.

•Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I. The recording medium was a thin strip of one half inch (12.65 mm) wide metal, consisting of nickel-plated bronze (called Vicalloy). Recording density was 128 characters per inch (198 micrometre/character) on eight tracks.

•The major advantage of magnetic tape drive is its lower cost per bit. •The highest capacity tape media are generally on the same order as the largest available disk drives (about 1 TB in 2007.) •Tape has historically offered enough advantage in cost over disk storage to make it a viable product, particularly for backup, where media removability is necessary.

Use in Computer Storage•Tape storage has always been used with large computer systems. Modern usage is primarily as a high capacity medium for backups and archives. •As of 2008, the highest capacity tape cartridges (Sun StorageTek T10000B, IBM TS1130) can store 1 TB of data without using compression.

Solid State Storage Device•A solid-state drive (SSD) is a data storage device that uses solid-state memory to store persistent data. A SSD emulates a hard disk drive interface, thus easily replacing it in most applications.Solid State Device either uses DRAM or Flash Memory. An SSD using SRAM or DRAM (instead of flash memory) is often called a RAM-drive.

•The original usage of the term solid-state (from solid-state physics) refers to the use of semiconductor devices rather than electron tubes, but in this context, has been adopted to distinguish solid-state electronics from electromechanical devices as well. With no moving parts, solid-state drives are less fragile than hard disks and are also silent (unless a cooling fan is used); as there are no mechanical delays, they usually employ low access time and latency.

•SSDs have begun to appear in laptops, although as of 2009 they are substantially more expensive per unit of capacity than hard drives.

Figure: ADTRON Solid Storage Drive

Figure: Picture of a Magnetic HDD Figure: Illustration on how magnetic HDD works

Need of SSDMagnetic storage device consists of a read write head and the platter. The platter has to spin to bring the area to be written under the read write head in order to write or read data.

We can easily understand that it takes some time. Some milliseconds spend while a part of the platter travels to the right place to be rewritten a piece of data and we can assume how long does it take when a piece of data is accessed at the same time from lots of computer. At the top of that magnetic hard drive stores the data randomly which makes the head move back and forth to its needed location, which further increases the time, consumed. Especially in the websites and other computer operations there could be millions of people who are accessing the data from storage. According to reports the fastest hard disk takes 5 milliseconds to for this propose. Now take Google’s storage for example where 3 billion people access their web server in a day.

SSD is to Rescue HDDAs its names suggest Solid State Disk doesn’t spin like conventional magnetic disk. It does not use any physical arm which we call read write head like in magnetic storage. It instead uses Flash Memory to read and write data. Flash memory is an EEPROM which consists of number of NAND and NOR logic gates.

The very reason SSD doesn’t need its read/write head to read and write by moving back and forth in the platter, it saves the time, which an operation looses while operating in the magnetic disks. And that’s why we can call SSD was invented to rescue the HDD.

HistorySolid State Storage was invented long ago, however it was immediately replaced by cheaper drum storage units.

First modern type SSD was developed by Storagetek in 1978.

In the mid-1980s Santa Clara Systems introduced BatRam, an array of 1 megabit RAM Chips and a custom controller card that emulated a hard disk.

In 2007 small notebooks started using SSDs of a few gigabytes capacity .

The SSD with the highest capacity now has 1 TB and developed by PureSilicon. Before that it was 640GB and was developed by ioDrive. Toshiba has announced that it will produces a SSD of 512 GB beginning 2001.

Although SSD has not yet gain mainstream popularity, with the trend of achieving high capacity into solid state drives It is expected to replace the traditional hard disks in Notebook computers very soon.

Two Types of SSDFlash Based•Most SSD manufacturers use non-volatile flash memory to create more rugged and compact devices for the consumer market. These flash memory-based SSDs, also known as flash drives, do not require batteries. Non-volatility allows flash SSDs to retain memory even during sudden power outages, ensuring data persistence. It performs better than conventional hard disks because of its negligible seek time.•Capacitors are used for the storage of the data or some form of battery. Cache is also used in SSD which operates in the same way cache works in Hard Disk. Cache is made of DRAM.

DRAM Based•SSDs based on volatile memory such as DRAM are characterized by ultra fast data access and are used primarily to accelerate applications that would otherwise be held back by the latency of Flash SDDs or traditional HDDs.

•DRAM-based SSDs usually incorporate internal battery and backup storage systems to ensure data persistence while no power is being supplied to the drive from external sources. If power is lost, the battery provides power while all information is copied from random access memory (RAM) to back-up storage. When the power is restored, the information is copied back to the RAM from the back-up storage, and the SSD resumes normal operation.

Current UsesRecently SSD has been being used in few potable laptops and and ultra mobile PCs with additional prices.

One of the first mainstream releases of SSD was the XO Laptop, built as part of the 'One Laptop Per Child' project. Mass production of these computers, built for children in developing countries, began in December 2007. These machines use 1024 MiB SLC NAND flash as primary storage which is considered more suitable for the harsher than normal conditions in which they are expected to be used.

Asus also uses 2,4 and 8 GB of Flash Storage in their Eee PC subnotebooks.

Apples has recently started providing Flash storage for additional charge. Apple provides this model of computer with 120 GB of solid state drive for additional 550 USD.

Lenovo ThinkPad X300 with a 64Gbyte SSD is available to consumers in some countries. And X301 of the same model of Lenovo is available with with 128GB SSD.

Advantages Over Normal HDD# Faster start-up, as no spin-up is required (RAM & Flash).

# Typically, fast random access for reading, as there is no read/write head to move (RAM & Flash).

#No noise: a lack of moving parts makes SSDs completely silent.

#For low-capacity flash SSDs, low power consumption and heat production when in active use, although high-end SSDs and DRAM-based SSDs may have significantly higher power requirements (Flash).

#High mechanical reliability, as the lack of moving parts almost eliminates the risk of mechanical failure (RAM & Flash). #Larger range of operating temperatures. Typical hard drives have an operating range of 5-55 degrees C. Most flash drives can operate at 70 degrees, and some industrial grade drives can operate over an even wider temperature range.

Disadvantages of SSD#Cost: As of mid-2008, SSD prices are still considerably higher per gigabyte than are comparable conventional hard drives: consumer grade drives are typically US$2.00 to US$3.45 per GB[10][21] for flash drives and over US$80.00 per GB for RAM-based compared to about US$0.38 or less per gigabyte for hard drives.

# Capacity: Capacity of SSD is as of now far lower than the conventional HDD however the storage capacity is expected to increases rapidly.

#Lower storage density: Hard disks can store more data per unit volume than DRAM or flash SSDs, except for very low capacity/small devices.

#Power: DRAM based SSD require more power than hard disks, when operating; and they still use power when the computer is turned off, while hard disks do not.

Future of SSD

As of now Windows Operating system is not optimized for SSD. Windows has long history and they haven’t really focused on other than magneto-mechanical HDDs. However Windows OS7 is said to be optimized for Solid Storage Devices which is still in beta stage.

As the popularity of SSD is rising the upcoming version of all Operation Sytesms including Windows, Linux and Mac OSX is expected to be optimized for Solid Storage Devices.

Flash Storage DevicesFlash Storage is pretty much same as solid storage devices. The main deference is flash storage is designed for more portability. Flash storage comes is smaller sizes. Pen drives and memory cards are the example of flash storage.

In fact flash storage is component of one of the two kind of Solid State Storage.

This is partially true as solid state drives and USB flash drives both use the same type of non-volatile memory chips that retain their information even when they have no power.

Flash drive is designed to be external to the computer system, an SSD is designed to reside inside the computer in place of a more traditional hard drive.

Characteristics of Flash StorageFlash storage is non-volatile.

Flash storage comes in very portable size.

Some of the forms of Flash Storage Device is Pen Drive, Memory Cards.

Flash memory is also used as secondary memory is some ultra-portable computer as well as PDAs.

Flash memory is sometimes called Flash RAM.

USB Flash StorageUSB flash drive consists of a NAND-type flash memory data storage device integrated with a USB (universal serial bus) interface. USB flash drives are typically removable and rewritable, much smaller than a floppy disk (1 to 4 inches or 2.5 to 10 cm), and most USB flash drives weigh less than an ounce [1]. Storage capacities typically range from 64 MB to 64 GB[2] with steady improvements in size and price per gigabyte. Some allow 1 million write or erase cycles[3][4] and have 10-year data retention,[5] connected by USB 1.1 or USB 2.0.

USB flash drives offer potential advantages over other portable storage devices, particularly the floppy disk. They have a more compact shape, operate faster, hold much more data, have a more durable design, and operate more reliably due to their lack of moving parts. Additionally, it has become increasingly common for computers to be sold without floppy disk drives. USB ports, on the other hand, appear on almost every current[update] mainstream PC and laptop. These types of drives use the USB mass storage standard, supported natively by modern operating systems such as Windows, Mac OS X, Linux, and other Unix-like systems. USB drives with USB 2.0 support can also operate faster than an optical disc drive, while storing a larger amount of data in a much smaller space.

Memory CardsA memory card or flash memory card is a solid-state electronic flash memory data storage device used with digital cameras, handheld and Mobile computers, telephones, music players, video game consoles, and other electronics. They offer high re-record-ability, power-free storage, small form factor, and rugged environmental specifications.

There are many different types of memory cards and jobs they are used for. Some common places include in digital cameras, game consoles, cell phones, and industrial applications. PC card (PCMCIA) were among first commercial memory card formats (type I cards) to come out in the 1990s, but are now only mainly used in industrial applications and for I/O jobs (using types I/II/III), as a connection standard for devices (such as a modem).

Many video game consoles have used proprietary solid-state memory cards to store data. In recent years read-only optical discs have replaced these memory cards in most current home console systems. However most portable gaming systems still rely on custom memory cartridges, due to their low power consumption, smaller physical size and reduced mechanical complexity. Microsoft XBOX, Nitendo and Sony Playstations are some of those game consoles.

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