Module 2.1: Mass Storage Devices

Dual Drive

storage configuration with separate SSD and HDDs installed. Here the system chipset and storage drivers make the caching decisions

Hybrid Drive

storage device that combines a SSD and a HDD. The SSD is used as a cache holding data that is used often. The HDD is only spun when non-cached data is needed

GUID Partition Table (GPT)

the boot info is not restricted to a single sector; GPT is associated with UEFI firmware but can also be supported by legacy BIOS firmware if supported by the OS; there are no restrictions on the number and size of the partitions

life expectancy

the duration for which the device can be expected to be reliable

Internal Transfer Rate (Data/Disk Transfer rate)

the speed at which read/write operations are performed on the disk

Access time

the time it takes a storage device to locate its stored data.

Partitioning

to divide a hard drive into separate storage areas on the same physical disk

RAID 0

A RAID array in which every time data is written to disk, a portion (block) is written to each disk in turn, creating a "stripe" of data across the member disks. RAID 0 uses the total disk space in the array for storage, without protecting the data from drive failure. (2)

FAT32 (File Allocation Table)

A file system that was popular in earlier versions of Windows (such as Windows 95, Windows 98, Windows Millennium Edition, Windows NT, and Windows 2000).

NTFS (New Technology File System)

A file system used on Windows-based systems. It is more efficient and provides much more security than do FAT-based file systems.

MTBF (Mean Time Between Failures)

A measure of the average time between failures in a system - the higher the amount, the more reliable the thing is.

RAID 5

A technique that stripes data across three or more drives and uses parity checking, so that if one drive fails, the other drives can re-create the data stored on the failed drive. RAID 5 drives increase performance and provide fault tolerance. Windows calls these drives RAID-5 volumes.

RAID 1

Also called mirroring, this RAID array type provides fault tolerance because all the data is written identically to the two drives in the mirrored set. (2)

Disk Defragmentation

An optimization utility that will reorganize files and fragments to place related ones nearer to each other.

latency time

The average amount of time required for the desired data to rotate around to the read/write head

hard disk drive (HDD)

The computer's nonvolatile, primary storage device for permanent storage of software and documents. New drives have the ability to hold up to 8 TB of data. 3.5" are most common, while 2.5" are used in laptops

Master Boot Record (MBR)

The first sector on a hard drive, which contains information about the different partitions on the disk, plus the location of the active boot sector

revolutions per minute (rpm)

The number of times per minute that a hard disk platter rotates.

seek time

The time it takes for a read/write head to move to a specific data track; one of the delays associated with reading or writing data on a computer disk drive.

Solid State Drive (SSD)

a storage device that typically uses flash memory to store data, instructions, and information. Does not contain any moving parts

Boot sector

First sector on a PC hard drive or floppy disk, track 0. The boot-up software in ROM tells the computer to load whatever program is found there. If a system disk is read, the program in the boot record directs the computer to the root directory to load the operating system

disk striping

Process by which data is spread among multiple (at least two) drives. Increases speed for both reads and writes of data. Considered RAID level 0 be- cause it does not provide fault tolerance.

Redundant Array of Independent Disks (RAID)

a collection of disk drives used for fault tolerance and improved performance, and is typically found in large network systems

RAID 10

a combination of RaID 1 and RaID 0 that requires at least four disks to work as an array of drives and provides the best redundancy and performance.

External Transfer Rate (Transfer rate)

measures how fast data can be transferred through the bus to the CPU