Optical disk is an electronic data storage medium from which data is read and written to by using a low-powered laser beam. It is flat, circular, plastic or glass disk on which data is stored in the form of light and dark pits. The laser beam reads the pits and the data can be accessed. There are three basic types of optical disks:

• Read-only optical disks: The optical disks, which are recorded at the time of manufacture and cannot be erased. CD, CD-ROM, DVD-ROM, and DVD-Video are the read-only disks.

• WORM: WORM stands for write-once, read many. The optical disks that can be recorded by the user only once but cannot be erased. After they have been recorded once, they behave like a read-only optical disk CD-R, DVD-R, and WORM disks are write-once.

• Rewritable/Magneto-optic disks: The optical disks that can be erased and written to with the new information. CR-RW, DVD-RAM, DVD-RW, and magneto-optic disks and Data play are rewritable. Rewritable disks use magneto-optic or phase change technology.

An optical disk offers many advantages over magnetic storage media.

• Highest storage capacity

• Low cost per Megabyte of storage

• Environmental condition tolerance

• High data stability

• Long media life

An optical disk has much more storage capacity on the order of gigabytes, than a magnetic disk. It can hold up to 6GB of data in comparison to 1.44 MB of a diskette. Optical disks are inexpensive to manufacture. Data stored on optical disks is resistant to power surges or magnetic disturbances, such as head crashes or corruption form stray magnetic fields. Hence, they provide high data stability. Optical disks are less vulnerable to extremes of hot and cold as
compared to the magnetic disks. Optical disks have long media life than magnetic disks.

OPTICAL STORAGE DEVICES

CD-ROM

CD-ROM: is an abbreviation of Compact Disc Read-Only Memory. A CD-ROM is a CD that contains computer data, which cannot be read or rewritten. In
computers, CDROM is the most commonly used optical storage technology. CD-ROM is a compact disc that contains information, which is accessible by a computer. It is composed of polycarbonate plastic, thin reflective metal layers, made of aluminium and a lacquer coating. Data is stored on the disc as a series of light and dark pits; the light portion refers to the spaces between the pits. A laser beam reads the pits and the data can be accessed.

CD-ROM is an adaptation/EXTENSION of the compact disc that is designed for music storage and playback. The format of CD-ROM is very similar to an audio CD; the only difference being the standards used to store data. A standard 120 mm CD-ROM holds up to 700 MB of data, or about 70 minutes of audio. This may mean that One CD can contain over one thousand novels; an average novel being composed of 60, 000 words. Once the data is written to a standard CD-ROM disc, it cannot be altered or rewritten.

A CD-ROM can be read using a CD-ROM drive, which is almost common on the personal computers. A CD-ROM drive may be connected to the computer in several different ways depending on the type of interface, such as:

• IDE (ATA)

• SCSI

• SATA

• Firewire

• USB

Almost all modern CD-ROM drives can play audio as well as video CDs.

CD-ROM STANDARDS

CD-ROM format provides an outstanding solution to the problem of storing large digital files. Several formats are used for data stored on CD-ROMs. These include Red book standards for audio-CD, White Book and Yellow Book for CD-ROM. An ISO 9960, which defines the standard file system of a CD-ROM is due to be replaced by ISO 13490.

CD-ROM FORMAT

One CD-ROM sector contains 2352 bytes, which is further divided into 98 24-byte frames. A CD-ROM contains a third layer of Reed-Solomon error correction in order to achieve improved error correction and detection.

Mode-1 CD-ROM: It has full three layers of error correction data, which contains 2048 bytes of the available 2352 per sector.
Mode-2 CD-ROM: It is mostly used for video files, which contains 2336 user-available bytes per sector.

CD-ROM SPEEDS AND USES

+ Early CD-ROM drives were known as single-speed and could read the data at the speed of 150 KBps.

+ CD-ROM drives can transfer data up to the speed of 7800 KBps

+ CD-ROM can store audio, video, text and program instructions. It is used to store software programs.

DVD-ROM

DVD-ROM: is an abbreviation of Digital Versatile Disc- read only memory. DVD-ROM is an optical disc storage media format that can be used for data storage, which includes movies with high video and sound quality. DVD-ROM is a non-volatile optical storage medium similar to CD-ROM, which contains computer data that cannot be erased or rewritten. These DVDs are read-only disks that have storage capacity for 133 minutes of high quality video, in format, and audio full- length feature film. The discs are pressed in a similar fashion as the CDs. The reflective surface is gold or silver colored.

DVD-ROM can be accessed using a DVD-ROM drive attached to the personal computer. DVD-ROM drives are backward compatible, i.e. they are also capable of reading CD-ROMs and audio CDs as well. The DVD-ROM supports disks with capacities of 4.7 GB to 17 GB and access rates of 600 KBps to 1.3 MBps. A standard DVD disc store up to 9.4 GB of data. DVD-ROMs are of same size as a compact disc, but holds data about 7 times more. DVD can store that much of data because both the sides of a disc are used, with sophisticated data compression technologies.

DVD-ROM is a variation of CD-ROM that is being used in place of CD-ROMs in many personal computers. All DVD-ROMs contain a file system, UDF, which is an extension of the ISO 9660 Standard used for data CDs.

CD-RW

CD-RW is an abbreviation of compact disc-rewritable. It is a recordable CD format that can be erased and rerecorded multiple times, just like a floppy disk or a hard disk. It is a rewritable version of CD-ROM. CD-RW disc is round plastic, about 5 inches in diameter. CD-RW disks can be played or recorded in the CD-RW drive only. These disks behave unusable when put in a regular CD-drive or a CD-R drive cannot be played. A CD-RW drive can read everything except a DVD.

A CD-RW can hold 650 Megabytes of data (unlimited number of times) written by a CD-RW drive. CD-RW cannot be selectively overwritten but can be extended. CD-RWs must be closed before they can be read in a normal CD-ROM drive. CD-RW disks cannot be read using a CD-ROM drive built before 1997. CD-RWs can be randomly read and written because of the variation of UDF format. CD-RW disks and drives are more expensive than a regular CD-ROM drive or media. A CD-RW disc can be read optically by laser light.

DVD-RW

DVD-RW: stands for Digital Versatile Disk-Rewritable. It is a re-recordable optical disc, which can record up to 4.7 GB per side in a similar fashion to a CD-RW. DVD-RW supports sequential read/write access i.e. the device may need to wait for the correct location in a constantly revolving medium. The information stored on DVD-RW can be erased and rerecorded over multiple times without damaging the medium.

DVD-RW is a phase-change erasable format based on DVD-R, using similar mark length, track pitch and rotation control. The format is supported by the DVD Forum. DVD-RW is also called “DVD Dash RW” and “DVD Minus RW”.

DVD-RW can be played in many DVD drives and players. Depending on quality, recording time varies from 1 hour to 6 hours.

Secured

Flash Disk is a portable storage device using Flash Memory. Flash Disk is one of the most practical and secured portable storage device used nowadays. Flash disk is secured because unlike other portable storage devices such: MMC, SD, Transflash, Flash disk has built in controller chip, which enable flash disk to be installed with security software and many more portable softwares. As for the other portable storage device mentioned, their controller are built in the card reader, so basically any person whose own the card reader can open any kind of MMC, SD, or Transflash that they found. So if u would like to purchase a flash disk, make sure that it is supported with security software, it is really a waste if u had a flash disk with out using its security software. Flash Disk is an excellent alternative for secured portable data storage.

Fashionable, Compact and Durable

Nowadays, the size of flash disk is getting smaller and slimmer, vary between manufacturers, between 4 cm up to 7 cm long, with width of only 0.5 – 1 cm. Not only that, flash disk external housing is being manufactured in very stylish and fashionable design. Beside the artificial function, Flash disk’s external housing makes it very durable. Flash disk external housing makes flash disk to be dust proof, shock proof, magnetic field proof, and even water proof (for certain products). Because flash disk is so durable, we can expect long data retention rate of 1.000.000 read/write cycles. Our advice is do not choose too small flash disk, cause there is a good chance u might loose it.

High Speed Usb 2.0

Today technology has enable flash disk’s data transfer speed range between 1.5 Mb/sec (Usb 1.1) up to 480 Mb/sec(Usb 2.0, and only possible if your Usb port really support High Speed Usb 2.0). In daily practice, none of our Usb port really supports high speed usb 2.0, which makes the average data transfer speed of usb 2.0 flash disk vary between 14 Mb/s up to 24 Mb/s.

SanDisk is one of the world in manufacturing, research, retail, product design Protection of consumers and brand USB flash memory. The product portfolio SanDisk USB drives are for businesses and consumers, flash cards for digital camcorders, digital cameras and mobile phones, embedded in the memory Solid-State-drives for computers and mobile devices. This flash drive, the latest technology blocked and prevents the introduction of malicious software in the SanDisk flash drive, even if the flash drive is used outside the firewall.

McAfee Inc. is a security technology company. McAfee headquarters in Santa Clara, California, USA. McAfee offers the best and proactive services and solutions for security and protection of networks and systems in the world. McAfee has unparalleled experience and expertise in the field of security and to authorize the public authorities, businesses, service providers and users with the ability to avoid problems, blocking attacks, and improve their safety and runway.

McAfee and SanDisk have “Cruzer Enterprise USB drive, McAfee Anti-Malware. It protects users into a Universal Serial Bus route data leaks. SanDisk flash drive was also “McAfee scanning engine. It fully recognizes the heuristics and made threats, the two are not known, and is known. This flash drive, the latest technology blocked and prevents the introduction malware in the SanDisk flash drive, even if the flash drive is used outside the firewall. SanDisk Cruzer is the best solution and ease of information and telecommunications technology Services and mobile workforce, where priority is data security. It allows users access to data and secure, and fully protected. The addition of security technology of McAfee, the customer may by SanDisk flash drive to continue to develop and improve their security measures for mobile data.

SanDisk flash drive automatically search for malware and prevents the transmission of the file on the flash drive security detection of infection on the host system. Malware is a program, known as “malware”, with the health code (viruses, trojans, worms). The establishment of the definition files and virus scanning engine, prohibits the installation of malicious software with the laptop and the internal drive of the infected host is against it. Each file, copy and saved it for the SanDisk USB drive is scanning engine. As the mobile workforce and new threats in line to take, it is very important for companies, the measures necessary to protect the mobile devices from viruses, worms, malicious software.

Analysis engine is, for many years of experimentation and is the foundation of the Anti-Malware McAfee. The SanDisk Cruzer users are fully protected and free of malicious software malicious code. SanDisk flash drive protects data with AES 256-bit encryption hardware. So, during the creation process, users have a password. The combination of password and encryption in case the reader is lost or stolen, a particular difficulty for unauthorized access to information on the flash player. Therefore, the company value and valuable information and can be free no no of users. SanDisk flash drive is durable, reliable and advanced, and the latest technologies, services and their clients.

Even the largest USB flash drive is still smaller than most people thumbs. Since we want these devices to many sites, it is a good chance that we can lose. If this happens, most of us can only hope that nothing sensitive on the hard disk. However, this is not the only thing you can do.

There are some basic rules of USB flash drive security measures are available.

If your flash drive of some sensitive information that you hope the online, the next day, security measures ranging from security encryption partitions Options.

Secure partitions are a rudimentary form of security – a password-only partition on the hard disk with a program by the manufacturer, is a partition and public safety.

In most cases it is not possible, access to these partitions on the same time, it is often necessary for security in the partition, hidden from the public. Not all controls this limitation. Use a profit, someone else could be re-partition the hard disk. However, they do not have access to the information you have on the partition to save.

There are also other USB flash drives, more specialized, they offer the same type of security, password-protected partition. They are also encrypt data on this score, making it much harder for people to access your data. While encryption algorithms that can be encrypted on your USB drive is an extra layer of data security.

The definition of this page to the engines, encryption, is that some of them only in the encryption software, the results are less effective on the drive, if encryption is enabled. Very few manufacturers use a hardware engine to encrypt and decrypt files at a higher speed to prevent performance when you click on a partition to ensure that the use of encryption.

The problem of the safety of these approaches is, above all in terms of software, most manufacturers of USB flash drives only Windows-based software support.

What does this mean for Mac users and men, a Linux distribution or another operating system less?

The security of USB flash drives is often a question of good governance among them. While it is possible to access scores on almost all systems of access to the partition requires as a general rule, access to Windows.

USB flash drive security is still in children’s shoes, because these drives are not used regularly, those with a need to safeguard their data. When it is more widespread and the need for security increases, expect flash drive options to improve safety and. For now, partitioning and encryption are the main options available, though.

Windows users can have the chance of these two options for the effective conservation of their data. However, users of the operating systems that are not compatible with the software on the hard drive should just try not to rent its USB flash drives to fall into the wrong hands.