Chapter 3-IT Flashcards
Storage
Storage system
Storage medium-is the hardware where the data is stored (flash memory etc. DVD disc)
Storage device-is the hardware into which the storage medium is inserted (DVD drive)
Volatility and Random vs Sequential Access
Volatility-storage media are nonvolatile, and therefore is used for data to be saved for later use
Random-Direct access, allows data to be retrieved from any location on the storage medium
Sequential access-That retrieval of data can occur only in the order in which it was physically stored o the storage medium etc magnetic tape
Logical vs Physical Representation
Logical-How we view how data is stored
Physical-How computers view how data is stored
Types of storage technology
Magnetic(conventional hard drives)
Optical(optical discs)use light rays
Electrons(flash memory media)
Hard drives
Stores most programs and data for personal computer
Available with built-in encryption that limits access to only authorized users
Magnetic Hard drive
HDD contains particles on the metal disks inside the drive that are magnetized to represent the data’s 0s and 1s
Hard disk organization
Tracks-concentric paths on the disk where data is recorded
Sectors-Are small pieces of a track
Clusters-Consist of one or more sectors(smallest addressable area of a disk)
Cylinders-are a collection of tracks located in the same location on a set of hard disk surfaces
Magnetic hard drive technologies
Traditional-longitudinal magnetic recording aligns magnetic particles on a hard disk horizontally, parallel to the hard disk’s surface
Newer-Perpendicular magnetic recording (PMR) places bits upright and closer together to increase capacity and reliability
Data recovery experts
Recover data from damaged storage devices
Used when devices are physically damaged or just stop working
It is important to backup data to prevent data loss
Solid state drives
Uses flash memory technology to store data
Uses less power and has no moving parts
Generate less heat and no noise
Much faster than magnetic hard drives, but more expensive
The norm for netbooks, other portable devices
Solid state hybrid drives
Uses a combination of magnetic disks and flash memory chips
The data that is most directly associated with performance is stored in the flash memory
Nearly as fast as solid-state drivers(SSDs)
Slightly more expensive than magnetic hard disk drives
Reduces the number of times the magnetic disks need to be read/written to
Internal hard drives
Permanent storage devices located inside the system unit
External hard drives
Transport large amounts of data from one computer to another, for backup, and for additional storage, typically powered by the computer throughout the USB port
Disk access time
Is the total time that it takes for a hard drive to read or write data
Consists of seek time, rotational delay, data movement time
Disk cache
Consists of memory used in conjunction with a magnetic hard drive to improve system performance
Consists of RAM-based disk cache located inside the hard drive case
Can speed up performance ad save battery life and reduces wear and tear. Stores copies of data and programs that are on the HD and that might be needed soon in memory to avoid having to re-read it
Hard drive partitioning
Partitioning divides the physical capacity of a single drive logically into separate areas, called partitions
Each partition functions as an independent hard drive ,referred to as logical drives
Increases efficiency(small drives use smaller clusters)
Partition are used to create
A recovery partition(to restore the computer to its earlier state)
A new logical drive for data(Easier to locate ad back up or to upgrade an OS)
A dual boot system(using two different OS on the same drive)
File system vs interface standards
File system is the method the OS uses to store and organize file’s .It determines the partition size, cluster size, max drive size, max file size
Interface standards determine how a drive connects to the computer