1. Storage
Chapter 3

2. Learning Objectives
Name several general properties of storage systems.
Describe the two most common types of hard drives and what they are used for today.
Discuss the various types of optical discs available and how they differ from each other.
Identify some flash-memory-based storage devices and media and explain how they are used today.
List at least three other types of storage systems.
Summarize the storage alternatives for a typical personal computer.

3. Storage System Characteristics
Consist of a storage device and a storage medium
Medium is inserted into device to be used
Storage devices are typically identified by letter

4. Storage System Characteristics
Type:
Magnetic (conventional hard drives, tape)
Optical (CD/DVD’s)
Solid State: Electrons (flash memory media: USB, camera cards )
Location:
Local – internal or external
Remote – somewhere else
View:
Logical file representation:
The user’s view of the way data is stored
Physical file representation:
The actual physical way the data is stored on the storage media
Storage
Data can be stored randomly or sequentially

5. Data Retention Storage that lasts only while the power is on
Volatile
Non-Volatile
Storage that lasts only while the power is on
RAM
CACHE
REGISTERS
Storage that lasts regardless of the power HD CD
DVD
USB
ROM

6. MAGNETIC STORAGE
Hard Drives
Tape

7. Hard Drives Magnetic SSD Hybrid FEATURES Use Random Access
Can be Internal/External
Can be Partitioned for recovery/dual boot
Disk Access time – seek/rotate/move

8. Magnetic Tape Systems
Magnetic tape: Plastic tape with a magnetizable surface that stores data as a series of magnetic spots
Primarily used for backup and archival purposes
Sequential access only
Low cost per megabyte
Most tapes today are in the form of cartridge tapes
Read from and written to via a tape drive

9. OPTICAL STORAGE
CD’s DVD’s

10. Optical Discs Optical discs: store data optically (using laser beams)
Types of discs: CD, DVD, or Blu-Ray Disc (BD)
CD discs: hold 650 MB
DVD discs: hold 4.7 GB (single-layer) – can be dual layer
BD discs: hold 25 GB (single-layer) – can be dual layer
Burning: Process of Recording data onto disc
CD discs: Use infrared lasers
DVD discs: Use red lasers
BD discs: Use blue-violet lasers
Can be internal or external drives
External drives typically USB

11. Read-Only Discs (-ROM)
Read-only disc: end in –ROM
Surface is molded or stamped to represent the data
Can be read from, but not written to, by the user
CD-ROM (compact disc read-only memory)
DVD-ROM (digital versatile disc read-only memory)
BD-ROM (Blu-Ray disc read-only memory)
Normally come pre-recorded
Software programs
Clip art and other graphics
Music
Movies
Games (UMD, Wii, Xbox, etc.)

12. Recordable Discs (-R or +R)
Recordable disc: End in –R or +R
Can be written to ONCE, but cannot be erased and reused
Reflectivity of surface is changed by a laser (burned in)
CD-R discs
DVD-R/DVD+R discs
BD-R
Used for back up, sending large files to others, creating custom music CDs, storing home movies, etc.

13. Rewritable Discs (-RW or –RE)
Rewritable disc: end in –RW or –RE
Can be recorded on MANY TIMES - erased, and overwritten just like hard drives and USB’s
CD-RW
DVD-RW
BD-RE
Use phase-change technology where reflectivity of surface is changed by a laser and melted down for rewrite
Heating and cooling process is used to change the reflectivity of the disc
Can be changed back to erase the disc

14. SOLID STATE Uses ELECTRON STORAGE USB’s, Memory cards
(SD, xD, CF, etc.)

15. Flash Memory Systems Chip-based storage medium
No moving parts so more resistant to shock and vibration, require less power, makes no sound
Uses SSD - Solid-state storage system
Retain data – non-volatile
Most often found in the form of:
Flash memory cards
USB flash drives
Solid State or Hybrid hard drives
Very small and so are very appropriate for use with digital cameras, digital music players, GPS devices, notebook computers, mobile devices, etc.

16. Flash Memory Systems

17. Smart Cards
Smart card: Credit card-sized piece of plastic that contains some computer circuitry (processor, memory, and storage)
Stores small amount of data (about 64 KB or less)
Commonly used to store prepaid amounts of digital cash or personal information
Smart card readers are built into or attached to a computer, keyboard, vending machine, or other device
Some smart cards store biometric data
Can be used in conjunction with encryption and other security technologies

18. (could be magnetic, tape, electrons)
REMOTE STORAGE
Cloud, NAS, SAN
(could be magnetic, tape, electrons)

19. Other Types of Storage Systems
Remote storage: Using a storage device not directly a part of the computer being used
Cloud storage: Accessed via the Internet
Via Web sites (Flickr, Facebook, Google Docs, etc.)
Via online storage sites (Box.net, SkyDrive, etc.)
Network attached storage (NAS)
Storage device is connected directly to a network
Storage Area Network (SAN)
A whole network of hard drives, connected to a central computer
To use a storage area network, you must have access to the central computer

20. Costs for 1 MB storage Type/capacity Price 1 CD can store 650 MB
1 DVD can store 4.5 GB
1 Dual DVD can store 8.5 GB
1 BluRay can store 25 GB
1 Dual BR can store 50 GB
1 8GB USB
.34 per CD – appx /GB
.41 per DVD – appx /GB
.88 per DVD - appx /GB
1.29 per DVD – appx /GB
5.49 per DVD – appx /GB
7.99 per USB – appx /GB

21. Evaluating Your Storage Alternatives
Factors to consider:
Speed
Compatibility
Storage capacity
Convenience
Portability
Most users require:
Hard drive
CD or DVD drive
Flash memory card reader
USB port connecting USB devices

22. Review Questions
1. An online photo sharing site is an example of ______________________.
a. RAID
b. remote storage
c. holographic storage
2. True of False: Flash memory storage systems are called solid-state storage systems because they are nonvolatile.
3. A type of sequential storage that sometimes used today for backup purposes is _____________.