5.1.1 Storage Device Types

Learn the different types of long-term storage devices.

Hard Disk Drives (HDD)

A thick magnetic disc encased in a thicker protective shell. It consists of several aluminum platters, each having a read and write head. All the read/write heads are attached to a single access arm to prevent them from moving independently.

Each platter has circular tracks that cut through all the platters in the drive to form cylinders. The spinning of the platters is measured in revolutions per minute (RPM). The higher the RPM, the faster data on the hard drive can be accessed.

SCSI is a standard for transferring data between devices on internal and external computer buses. Though SCSI devices are most commonly used for tape storage devices and hard disks, they can also be used for devices such as CD-ROM drives, scanners, and printers.

Advantages vs. Disadvantages

• large storage capacities (16 GB up to several TB)

• cost per MB is cheap

• wide selection

• mostly internal devices, even though it's possible to get external ones

• prone to failure

• vulnerable to physical damage

Solid State Drives (SSD)

A flash device with the capacity similar to that of an HDD. They're used as the replacement to HDDs for storing the OS, applications, and data files.

Advantages vs. Disadvantages

• faster than HDDs
• no moving parts
• lower power consumption
• less susceptible to physical damage
• immune to damage caused by EMI
• smaller and lighter than HDDs
• EXPENSIVE.

Flash Memory

Store information using programmable, non-volatile flash memory. Common forms of flash memory include:

• CompactFlash cards
• SD cards
• SSD Cards
• MiniSD Cards
• MicroSD Cards
• Hybrid Cards (that combine HDD and SSD tech)
• Memory sticks

Advantages vs. Disadvantages

• reprogrammable memory
• retain content without power
• optimal for use in mobile devices like cameras
• highly portable
• larger capacity than CD/DVD discs
• relatively fast memory access
• cheap
• versatile

Non-Volatile Memory Express (NVMe)

A memory storage device designed to allow access to non-volatile storage media through the use of a PCIe bus. It's designed to work well with the low latency and internal parallelism of SSDs. NVMe reduces I/O overhead and improves functionality. NVMe devices come in three forms.

• Standard PCIe Expansion Cards
• 2.5in device that provide 4-lane PCIe interface through the U.2 connector
• SATA Express via M.2 connector (supports NVMe as the logical device interface)

Optical Discs

A storage medium that uses lasers for reading and writing info. The info is stored through pits in the reflective coating, and as the disc spins, the optical drive sends laser optics to the disk and receives the stored information through the deflected output.

Advantages vs. Disadvantages

• great for music/video

• portable and universal

• cheap

• long shelf life, relatively sturdy

• can store large amount of data

• slower

• smaller capacity

• some compatibility issues between disc formats and readers

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