Storage Types | CompTIA IT Fundamentals FC0-U61 | 2.5

In this video you will learn about the differences between various storage types such as:  volatile versus non-volatile, local storage types, local network storage types, and cloud storage services.

Volatile vs. Non-Volatile

Volatile storage is a type of computer memory that needs power to preserve stored data.  If the computer is switched off, anything stored in the volatile memory is removed or deleted.  There is only one type of volatile storage: random access memory (RAM). Non-volatile memory (NVM) is a type of computer memory that has the capability to hold saved data even if the power is turned off.  Unlike volatile memory, NVM does not require its memory data to be periodically refreshed. It is commonly used for secondary storage or long-term consistent storage.  There are many types of non-volatile storage, including magnetic (spinning disk) hard drives, solid-state drives, optical storage, flash drives, network storage, and cloud storage.

Local Storage Types

Local storage is the first type of storage available when you turn on a computer, tablet, or smartphone.  Local storage does not require an internet or even a network connection.

Random Access Memory (RAM)

RAM (also known as main memory, primary memory, or system memory) is a hardware device that allows information to be stored and retrieved on a computer.  When you turn on a computer, smartphone, or tablet, the operating system is loaded into the device’s RAM, followed by apps or other processes that are loaded at startup.  With desktops and many laptops, memory modules of various sizes can be installed to increase the amount of volatile storage available for the operating system, apps, and the data created, changed, or loaded. Memory modules for desktop computers are commonly known as DIMMs (dual inline memory modules).  Laptop memory modules are commonly known as SODIMMs (small outline DIMMs).

DDR4 DIMM for Desktops
SODIMM for Laptops

Before working with any memory modules, turn off the computer and unplug it from the AC outlet.  Electrostatic discharge (ESD) is a sudden flow of electricity between two electrically charged objects that can harm computer components.  Be sure to employ ESD protection in the form of an ESD strap and ESD mat.

Installing SODIMM RAM

Hard Drive

A hard drive (sometimes abbreviated as HD or HDD) is a non-volatile data storage device.  It is usually installed internally in a computer, attached directly to the disk controller of the computer’s motherboard.  It contains one or more platters, housed inside of an air-sealed casing. Data is written to the platters using a magnetic head, which moves rapidly over them as they spin.  Hard drives are available in 2 types:

  • Solid state
  • Spinning disk; using magnetic storage

Solid State Drive (SSD)

An SSD is a type of mass storage device similar to a hard disk drive.  It supports reading and writing data and maintains stored data in a permanent state even without power.  SSDs are rapidly becoming the system drive of choice for laptops and convertible computers as well as for performance-oriented desktop computers and servers.  These drives use various types of high-performance flash memory to store files, and they can be used for the operating system, apps, and data. Because there is no need to move read-write heads to various storage areas of the drive to locate data, SSDs are faster than mechanical hard drives and are not affected by shock.

SSDs can also be used as replacements for existing spinning-disk hard drives in laptops or desktop computers and are also available in external versions using USB 3.1 Gen 1 (aka USB 3.0) and USB 3.1 Gen 2 interfaces.  Windows 8.0 and later have built-in support for SSDs, but older versions of Windows require special configuration settings for use with SSDs. MacOS (OS X) 10.10.4 and later have built-in support for SSDs. Linux distributions (distros) based on the Linux kernel version 3.8 and later have built-in support for SSDs; however, it is recommended that you check the compatibility for a particular SSD and its controller with the vendor of your preferred Linux distro.

Typical SSD Hard Drive

Spinning Disk (HDD, SSHD)

A spinning disk is the mechanism with a hard disk drive to which memory is written.  With rotating plates attached to an arm that writes the data, the spinning disk mechanism physically resembles a record player (although it is sealed within an enclosure).  The plates are magnetized (similarly to cassette tapes) in order to store data that is written using copper heads. Although SSDs have become very popular as startup system drives, they still do not offer the cost per GB or capacity of spinning disk drives.  Spinning disk drives contain one or more aluminum or glass platters that have magnetic coatings. Read/write heads are moved to the correct location to read existing data and write new or changed data. A circuit board on the bottom of the drive assembly contains cache memory, the SATA controller chip, and SATA power and data interfaces.  Typical HDD capacities range from 500GB to 6TB, but high-capacity HDDs for desktops and small servers are now available in capacities as his as 12TB.

Standard Hard Drive

A solid-state hybrid drive (SSHD) is a logical or physical storage device that combines a faster storage medium such as solid-state drive (SSD) with a higher-capacity hard disk drive (HDD).  The intent is adding some of the speed of SSDs to the cost-effective storage capacity of traditional HDDs. The purpose of the SSD in a hybrid drive is to act as a cache for the data stored on the HDD, improving the overall performance by keeping copies of the most frequently used data on the faster SSD.  A SSHD resembles a standard HDD, but it also includes up to 8GB of high-speed flash memory. An SSHD is a combination HDD and SSD, offering up to 4TB of storage that can be accessed several times faster than with an HDD. SSDs are more expensive than spinning disk drives, however, they have many advantages over their rivals such as:  SSDs use smaller form factors so they can fit into smaller spaces, they run cooler, and they are much faster than spinning disk drives.


An optical drive is a type of computer disk drive that reads and writes data from optical disks through laser beaming technology.  Optical drives are fading from standard system configurations but are still useful for creating and installing operating system recovery disc images, creating and installing self-booting diagnostic apps, installing apps sold on DVD media, transferring information to other users, and creating DVD or Blu-ray movie discs.  Optical drives for desktop computers use a 5.25 inch form factor, and most have a pop-out tray for loading media.

Typical Optic Drive

Common optical drive markings are as follows:

  • LightScribe:  Can record labeling information on the label side of the media.  Requires special LightScribe media and software.
  • DVD-Multi Recorder:  Can read DVD-ROM (pressed) media, can read/write DVD-R, DVD-RW, and DVD-RAM media, and can erase and rewrite DVD-RW and DVD-RAM media.
  • RW DVD+R DL:  Can read DVD-ROM and can read/write DVD+R (single layer), DVD+R DL (dual layer), and DVD+RW (read/write/erase).
  • Compact Disc ReWriteable:  Can read CD-ROM (pressed) media, can read/write CD-R media, and can read/write/erase CD-RW media.  Ultra Speed drives support CD-RW discs with speeds from 16x to 24x. Other speed grades include High Speed (8x-12x), originally (1x-4x), and Ultra+ (32x).

Laptops with optical drives typically use a slimline drive with a pop-out tray.  A similar design is used for optical drives that connect via USB 2.0 or faster ports.  Media for optical drives can be divided into three categories:

  • Compact Disc (CD):  media has a capacity of 700MB; DVD and Blu-ray (BD) drives can also read and write CD media.
  • Digital Video Disk (DVD):  media has a capacity of 4.7GB (single-layer) or 8.4GB (dual-layer).  Blu-ray drives can also read and write DVD media.
  • Standard Blu-ray Disc (BD):  has a capacity of 25GB (single-layer), with enhanced versions holding more data.

Pressed CD, DVD, and Blu-ray media are read-only.  CD-R, DVD-R, DVD+R, and BD-R discs can be written to but not erased.  CD-RW, DVD-RW, DVD+RW, and BD-RE discs can be written to, erased, and rewritten.  DL discs feature two recording layers.

Windows Drive Letter Assignments

A Windows drive letter assignment (also known as a device letter) is a single alphabetic character A through Z that is assigned to a physical computer drive or drive partition.  Windows assign drive letters in the order that drives are connected to the system. The drive (SSD or spinning drive) where Windows is installed is the C: drive. If the system has an optical drive installed, that drive is normally assigned the drive letter D:.  Additional drives use drive letters E: or above. Windows can also assign network folders that are shared with a computer a drive letter. When you move a drive from one computer to another, it might be assigned a different drive letter based on the drive letters already assigned on that computer.

Flash Drives

A flash drive (also known as a USB flash drive, data stick, pen drive, memory unit, keychain drive, thumb drive, or a jump drive) is a portable storage device.  It is often the size of a human thumb and connects to a computer via a USB port. Flash drives are an easy way to store and transfer information between computers and range in sizes from 2GB to 1TB.  Flash drives can be divided into two categories: USB and card-based drives. USB flash drives can be plugged directly into a USB port. Card-based flash drives must be plugged into a flash card reader before they can be used.  Both types of flash drives are automatically assigned drive letters by Windows and are automatically recognized by macOS and by modern Linux distros.

Flash Drive

USB flash drives up to 32GB capacity are normally formatted using the FAT32 file system, and USB drives of 64GB capacity and higher are formatted using the exFAT file system.  These file systems are supported by recent versions of Windows, macOS, and Linux.

Most laptops and some desktop computers have flash memory card readers.  Laptop card readers generally accommodate only one or two types of cards:  typically SD/SDHC/SDXC and occasionally Sony Memory Stick Duo. Portable card readers and desktop internal card readers connect to a USB 2.0 or USB 3.0 (USB 31. Gen 1) port.  A multislot card reader might assign a different drive letter to each slot, enabling the reader to read multiple cards at the same time, or it might assign only one drive letter to all slots.

Memory Flash Card Reader

SD-family cards are commonly used in digital SLR (DSLR) and mirrorless cameras with interchangeable lenses as well as digital point-and-shoot cameras.  MicroSD and SD cards are available in three types:

  • Secure Digital (SD):  Capacities up to 2GB
  • Secure Digital High Capacity (SDHC):  Capacities up to 32GB
  • Secure Digital Extended Capacity (SDXC):  Capacities starting at 64GB
SD Cards

To enable a microSD card to work in a device that uses standard SD-family cards, use a microSD-SD adapter.

MicroSD Card

SD-family cards use two different speed measurements: 

  • C-class refers to write speeds in MBps (megabytes per second), with C10 (10MBps) being the fastest
  • UHS (Ultra High Speed) cards are available in U1 (10MBps write speeds) and U3 (30MBps write speeds).

For recording HD video, use at least a C10 or U1-rated card.

Local Network Storage Types

There are two types of devices that allow for a single storage location on a network which can make sharing files between devices easier and make data backup and restoration simpler:

  • Network-attached storage (NAS)
  • File server

Network-Attached Storage (NAS)

A NAS system is a storage device connected to a network that allows storage and retrieval of data from a centralized location for authorized network users and clients.  NAS is a self-contained storage device that contains one or more drives, a network interface, and is bundled with software to enable computers on the network to access the device. A NAS device built for use in business may have two or more drive bays, permit easy upgrading of drives, and might also provide for automatic mirroring (copying) of the contents of one drive to another (RAID 1).

Network Attached Storage (NAS)

File Server

A file server is a computer attached to a network that provides a location for shared disk access, i.e. storage of computer files (such as text, image, sound, video) that can be accessed by the workstations that are able to reach the computer that shares the access through a computer network.  Current operating systems for PCs enable one computer to share files and folders with others. However, for faster performance, business networks use file servers.

Typical File Server

A file server contains one or more drives, is connected to a network, and is designed to transmit and receive files from multiple devices at the same time using one or more Gigabit Ethernet or 10G Ethernet network adapters.  Data centers often use multiple file servers.

Cloud Storage Devices

Cloud storage is a model of computer data storage in which the digital data is stored in logical pools.  The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is typically owned and managed by a hosting company.  These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running. People and organizations buy or lease storage capacity from the providers to store user, organization, or application data.  As mobile computing devices (laptop and convertible computers, smartphones, and tablets) have become widespread, the need for storage that can be accessed anywhere has also grown. Cloud storage services enable both personal and business users to access their information and apps anywhere an internet connection is available. Services such as Google Drive, Microsoft OneDrive, Apple iCloud, Dropbox, Amazon Drive, and others offer subscriptions that provide access to specific amounts of cloud-based storage.

Google Drive Web Interface