| Technology |
|
|
|
Compact disc, recordable
(CD-R) or rewritable (CD-RW) and DVD |
- Low cost per megabyte
- Unlimited capacity with multiple discs
- Portable
- Widely-supported I/O interfaces
- Can be formatted for different data formats
- Long life
- High data density
- Immune to corruption once data is written (CD-R and DVD only)
|
- Limited capacity on one disc(though much greater than diskette)
- Slow to moderate read/write speed
|
- Data archiving
- Data distribution
- Data migration
- Localized file sharing
- Offsite storage
|
| Diskettes, 1.44 MB |
- Simple to use
- Portable
- Can be formatted for different data formats
|
- Limited capacity
- Limited read/write speed
- Not supported by many newer computers
|
- Local data transfer of small files
- Storage of small files or programs
|
| Hard drive, external |
- High read/write speed
- Can be moved among computers
|
- Limited capacity
- Awkward for data transfer among multiple computers
|
- Local backup
- Local archiving
|
| Hard drive, internal |
- Convenient; usually comes with the computer
- High read/write speed
- Convenient for use with single computer (but can be shared among multiple computers with proper support
- Most common form of data storage
|
- Limited capacity
- Without special support, confined to a single computer or server
|
- Storage in a single computer
- Swap files
|
| Removable storage (ZIP disks, JAZ disks, etc.) |
- Simplicity
- Portability
- Unlimited capacity with multiple disks
- Convenient for use with single computer
|
- Proprietary media
- Limited read/write speed
- High cost per megabyte
|
- Personal computing
- Local data transfer of small files
- Local backup
- Local archiving
|
| Solid-state storage (USB devices, flash memory, smart cards, etc.) |
- No mechanical parts
- High read/write speed
- Small form factor
|
- Limited storage capacity
- High cost per I/O operation
|
- Swap files
- Local data transfer
- Internet service providers
- Video processing
- Relational databases
- High-speed data acquisition
|
| Technology |
|
|
|
| Direct-attached storage (DAS) |
- Simplicity
- Low initial cost
- Ease of management
|
- Storage for each server must be administered separately
- Inconvenient for data transfer in network environments
- Server bears load of processing applications
|
- Data and application sharing
- Data backup
- Data archiving
|
| Disk library |
- High speed
- High storage capacity
- High data availability
|
|
- Disk-to-disk (D2D) backup
- Data archiving
- Near line storage
|
| Disk-to-disk-to-tape (D2D2T) |
- Redundancy
- High read/write speed
- Unlimited capacity with multiple tapes
|
|
- Incremental backups
- Storage virtualization
- Offsite storage
- Data archiving
|
Fibre Channel
(See Storage area network below) |
- Used to transmit data between devices at gigabit speeds
- Frequently used in storage area networks (SANs)
- Flexible in terms of distance
|
- High cost
- Management complexity
|
- Large databases
- Bandwidth-intensive applications
- Storage area networks (SANs)
- Offsite storage
- Mission-critical applications
|
iSCSI
(See Storage area network below) |
- Used to transmit data between devices using the Internet Protocol (IP)
- Frequently used in storage area networks (SANs)
- More flexible in terms of distance than Fibre Channel (but not as fast)
|
- May not compare favorably with Fibre Channel for large database transfers
- Management complexity
|
- Applications involving remotely distributed databases
- Storage area networks (SANs)
- Offsite storage
- Mission-critical applications
|
| Magnetic tape |
- Low cost per megabyte
- Portability
- Unlimited capacity with multiple tapes
|
- Inconvenient for quick recovery of individual files or groups of files
|
- Data archiving
- Limited-budget businesses
- Offsite storage
|
| Network-attached storage (NAS) |
- Fast file access for multiple clients
- Ease of data sharing
- High storage capacity
- Redundancy
- Ease of drive mirroring
- Consolidation of resources
|
- Less convenient than storage area network (SAN) for moving large blocks of data
|
- Data backup
- Data archiving
- Redundant storage
|
| Redundant array of independent disks (RAID) |
- High speed
- High storage capacity
- High data availability
- High reliability
- Security
- Fault tolerance
|
- Users may develop false sense of security
- Recovery from failure is difficult in some systems
- High cost for optimum systems
|
- Swap files
- Internet service providers
- Redundant storage
|
| Storage area network (SAN) |
- Excellent for moving large blocks of data
- Exceptional reliability
- Wide availability
- Fault tolerance
- Scalability
|
- High cost
- Lack of standardization
- Management complexity
|
- Large databases
- Bandwidth-intensive applications
- Mission-critical applications
|
