Computer Storage Systems and Technology Principles

Storage Media: Discrete hardware where data is physically kept (e.g., $DVD$ disc, flash memory card).
Storage Device: The hardware that reads from or writes to the medium (e.g., $DVD$ drive, card reader).
Drive Identification: Typically assigned letters; $C$ is the standard for the first hard drive, followed by optical drives ( $D$ , $E$ ), card readers ( $F$ , $G$ , $H$ , $I$ ), and external USB devices ( $J$ and beyond).
Volatility: Storage devices are nonvolatile, meaning data persists without power.
Access Methods: Most devices use random access (direct access); sequential access is used by magnetic tape drives.
Representations: Logical representation is the user's view (files and folders); physical representation is the computer's method using specific locations on the medium.
Core Technologies: Magnetic (hard drives), Optical ( $DVDs$ ), and Electrons (flash memory).

Magnetic Hard Drives: Use metal disks and read/write heads to magnetize particles representing $0s$ and $1s$ . Data is organized into circular tracks, pie-shaped sectors, clusters (the smallest addressable unit), and cylinders.
Solid State Drives (SSDs): Utilize flash memory, containing no moving parts, resulting in lower power consumption and zero seek or rotational delay.
Performance: Access time is the sum of seek time, rotational delay, and data movement time. Magnetic drives often use a disk cache (RAM or dedicated memory) to enhance speed.
Hybrid Hard Drives: Combine magnetic storage with flash memory used as a cache.
Partitioning: Logically divides a physical drive into separate areas (logical drives) for efficiency, recovery, or dual-booting.
File Systems: Determine cluster and file size limits; common systems include $FAT$ , $FAT32$ , and $NTFS$ .
Interface Standards: Systems for connecting drives include $Parallel ATA (PATA)$ , $Serial ATA (SATA)$ , $eSATA$ , $SCSI$ , $Serial Attached SCSI (SAS)$ , $Fibre Channel$ , and $iSCSI$ .

Mechanism: Uses laser beams to read and write data. Transitions between nonreflective pits and reflective lands represent binary data.
Capacity Comparison:
- $CD$ : $650\,MB$ to $700\,MB$ .
- $DVD$ : $4.7\,GB$ (single-layer) to $8.5\,GB$ (dual-layer).
- $BD$ (Blu-Ray): $25\,GB$ (single-layer) to $50\,GB$ (dual-layer).
Optical Drive Compatibility: Usually downward compatible; recording is known as burning.

Characteristics: Non-volatile chips used in $SSDs$ , digital cameras, and mobile devices.
Formats: Embedded (built-in) or removable cards such as $Secure Digital (SD)$ , $SDHC$ , $SDXC$ , $CompactFlash (CF)$ , and $Memory Stick$ .
USB Flash Drives: Small, portable drives connecting via $USB$ ports; can include biometric security features like fingerprint readers.

Remote Storage: Accessed via network or internet. Includes $Network Attached Storage (NAS)$ for local networks and $Storage Area Networks (SAN)$ for large environments.
Cloud Storage: Online services like $SkyDrive$ , $Box.net$ , and $Google Docs$ provide internet-based access and backup.
Smart Cards: Credit card-sized plastic containing circuitry for about $64\,KB$ of data, often for digital cash or biometrics.
Holographic Storage: An emerging $3D$ technology using blue lasers for high-capacity, high-speed data retrieval.
RAID: $Redundant Arrays of Independent Disks$ provide fault tolerance via striping ( $RAID 0$ ) or mirroring ( $RAID 1$ ).
Magnetic Tape: A low-cost, sequential access medium used for archival and backup purposes.

Question: Of the following three options, the storage media that would hold the most data is a(n) internal hard drive, $USB$ flash memory drive, or portable hard drive?
Response: Internal hard drive.
Question: True or False: Hard drives typically contain more than one metal hard disk.
Response: True.
Question: The circular rings on a magnetic disk on which data is stored are called?
Response: Tracks.
Question: The capacity of the typical $CD$ disc is $50\,GB$ , $650\,MB$ , or $4.7\,GB$ ?
Response: $650\,MB$ .
Question: True or False: A $DVD-RW$ disc can be written to and rewritten to.
Response: True.
Question: The tiny depressions, dark areas, or otherwise altered spots on an optical disc that are used to represent data are called?
Response: Pits.
Question: An online photo sharing site is an example of $RAID$ , remote storage, or holographic storage?
Response: Remote storage.
Question: True or False: Flash memory storage systems are called solid-state storage systems because they are nonvolatile.
Response: False.
Question: A type of sequential storage that is sometimes used today for backup purposes is?
Response: Magnetic tape.