1. Servers Redundant Array of Inexpensive Disks (RAID) –A group of hard disks is called a disk array FIGURE 14-10 Server with redundant NICs

2. RAID Level 0—Disk Stripping Simple implementation of RAID in which data are written in 64 KB blocks equally across all disks in the array FIGURE 14-11 RAID Level 0—disk stripping

3. RAID Level 1—Disk Mirroring Data from one disk are copied to another disk automatically as the information is written FIGURE 14-12 RAID Level 1—disk mirroring

4. RAID Level 3—Disk Stripping with Parity ECC Disk stripping with a special type of error correction code (ECC) Term parity refers to the mechanism used to verify the integrity of data by making the number of bits in a byte sum to either an odd or even number TABLE 14-1 Use of parity bits to achieve parity

5. RAID Level 3—Disk Stripping with Parity ECC Parity error checking –Process of comparing the parity of data read from disk with the type of parity used by the system FIGURE 14-13 RAID Level 3—disk stripping with parity ECC

6. RAID Level 5—Disk Stripping with Distributed Parity Data are written in small blocks across several disks FIGURE 14-14 RAID Level 5—disk stripping with distributed parity

7. Server Mirroring and Server Clustering Server mirroring –Fault tolerance technique in which one server duplicates the transactions and data storage of another Server clustering –Fault tolerance technique that links multiple servers together to act as a single server

8. Data Backup Copy of data or program files created for archiving purposes Vault –Tape storage library FIGURE 14-15 Examples of backup tape media

9. Tape Backups FIGURE 14-16 Tape drive on a medium or large network