Storage Devices

Storage Device Facts

When selecting a storage solution, first consider the type of storage device. The following table compares various storage devices.

Device Type	Description
Hard disk	Some of the advantages of hard disks are: They have lots of storage (usually more than 100 gigabytes, whereas most floppies have a maximum storage capacity of 1.4 megabytes). They are significantly faster than floppy disks. The cost per MB (or GB) is cheap. Some of the disadvantages of hard disks are: Many hard disks are internal devices, though you can get external enclosures. They are prone to failure. They are sensitive to vibrations and drops. They are vulnerable to magnetic interference.
Optical discs	Optical discs such as CDs and DVDs are a storage medium that use lasers for both reading and writing information. Some of the advantages of optical discs are: They are great for music and video (they play in audio or video devices that aren't computers). They are portable and universal. They are cheap. You can buy CDs that are recordable. They have a long shelf life and are relatively sturdy. Some of the disadvantages of optical discs are: They are slower than hard disks. They have a small capacity (650 MB for audio CDs, 4.7 GB for DVDs, 25 GB for Blu-ray). There are some compatibility issues between disc formats and readers.
Flash devices	Flash devices store information using programmable, non-volatile flash memory. Common flash devices are MMC, SD, memory sticks, and USB thumb drives. Some of the advantages of flash devices are: They can retain content without power. They are optimal for use in devices like cameras. They are highly portable. They have a larger capacity than floppy disks and CDs. Some have even more capacity than DVDs. They have relatively fast memory access. Some of the disadvantages of flash devices are: Their storage capacity is not yet comparable to the capacity of hard disks. Different card formats require different readers.
Solid state drives (SSD)	A solid state drive is a flash device with a storage capacity similar to a small hard drive. Solid state drives are used as replacements for hard disk drives for storing operating system, application, and data files. Some advantages of solid state drives: They are faster than hard drives They have no moving parts so they last longer They have lower power consumption than hard drives (good for laptops) They are less susceptible to physical damage (from dropping) and immune from magnetic fields They are smaller and lighter than hard drives The main disadvantage currently for solid state drives is cost--they are several times more expensive than comparable hard drives. However, their advantages make them a good choice, especially for portable devices.

After you have selected the type of storage device, you might have a choice to make regarding the interface type. The following table describes the most common storage device interfaces:

Interface	Description
PATA	PATA (also called EIDE, IDE, and ATAPI) is a parallel ATA interface. ATA is the standard interface for transferring data from storage devices such as hard disk drives and CD-ROM drives. PATA: Is the most common and the least expensive interface for hard disks and CD/DVD drives. Allows two devices per channel. Most motherboards include two built-in channels. Use parallel communication (meaning devices share the same data transfer channel). Some disadvantages of PATA interfaces are: They have a maximum speed of 133 MB/s. Because both devices share the same channel, devices must be configured properly to avoid conflicts. They are being phased out and replaced.
SATA	Serial ATA is computer bus technology primarily designed for transfer of data from a hard disk. SATA: Is the successor to PATA. Uses serial communication (meaning each device is on its own channel). Is faster than PATA. Provides built-in support for disk protection methods. Provides for easy configuration--just connect the device to the SATA port. Supports external devices through the External SATA (also called eSATA) standard. eSATA is faster than USB and Firewire.
USB/Firewire	You can connect storage devices through the USB and Firewire buses. Storage devices that can be connected to the USB or Firewire bus include: External hard drives and CD-ROM drives. Internal hard drives in an external enclosure. These devices use a PATA or SATA drive in an enclosure that then connects to the system through USB or Firewire. However, an eSATA device connected to a SATA bus is faster than using an SATA drive in an external USB or Firewire enclosure. Flash memory card readers. USB and Firewire devices are highly portable and easy to connect.