3. Bandwidth and Processing Power ............................................................................................... 29

3.1. Bandwidth ........................................................................................................................ 29

3.1.1. Buses ................................................................................................................. 29

3.1.2. Datapaths........................................................................................................... 30

3.1.3. Potential Bandwidth Related Problems ............................................................ 30

3.1.4. Potential Bandwidth related Solutions ............................................................. 30

3.1.5. In Summary. . . .................................................................................................. 31

3.2. Processing Power ............................................................................................................. 32

3.2.1. Facts About Processing Power.......................................................................... 32

3.2.2. Consumers of Processing Power....................................................................... 32

3.2.3. Improving a CPU Shortage ............................................................................... 33

3.3. Red Hat Linux Specific Information ............................................................................... 36

3.3.1. Monitoring Bandwidth on Red Hat Linux ........................................................ 36

3.3.2. Monitoring CPU Utilization on Red Hat Linux................................................ 37

3.4. Additional Resources ....................................................................................................... 41

3.4.1. Installed Documentation ................................................................................... 41

3.4.2. Useful Websites ................................................................................................ 41

3.4.3. Related Books ................................................................................................... 42

4. Physical and Virtual Memory ...................................................................................................... 43

4.1. Storage Access Patterns ................................................................................................... 43

4.2. The Storage Spectrum...................................................................................................... 43

4.2.1. CPU Registers ................................................................................................... 44

4.2.2. Cache Memory.................................................................................................. 44

4.2.3. Main Memory   RAM .................................................................................... 45

4.2.4. Hard Drives ....................................................................................................... 46

4.2.5. Off Line Backup Storage .................................................................................. 47

4.3. Basic Virtual Memory Concepts...................................................................................... 47

4.3.1. Virtual Memory in Simple Terms ..................................................................... 47

4.3.2. Backing Store   the Central Tenet of Virtual Memory ................................... 48

4.4. Virtual Memory: the Details ............................................................................................ 48

4.4.1. Page Faults ........................................................................................................ 49

4.4.2. The Working Set ............................................................................................... 49

4.4.3. Swapping........................................................................................................... 50

4.5. Virtual Memory Performance Implications ..................................................................... 50

4.5.1. Worst Case Performance Scenario.................................................................... 50

4.5.2. Best Case Performance Scenario ...................................................................... 51

4.6. Red Hat Linux Specific Information ............................................................................... 51

4.7. Additional Resources ....................................................................................................... 54

4.7.1. Installed Documentation ................................................................................... 54

4.7.2. Useful Websites ................................................................................................ 54

4.7.3. Related Books ................................................................................................... 54

5. Managing Storage ......................................................................................................................... 57

5.1. An Overview of Storage Hardware.................................................................................. 57

5.1.1. Disk Platters ...................................................................................................... 57

5.1.2. Data reading/writing device .............................................................................. 57

5.1.3. Access Arms ..................................................................................................... 58

5.2. Storage Addressing Concepts .......................................................................................... 59

5.2.1. Geometry Based Addressing ............................................................................ 59

5.2.2. Block Based Addressing................................................................................... 60

5.3. Mass Storage Device Interfaces....................................................................................... 60

5.3.1. Historical Background ...................................................................................... 61

5.3.2. Present Day Industry Standard Interfaces ........................................................ 62

5.4. Hard Drive Performance Characteristics ......................................................................... 64

5.4.1. Mechanical/Electrical Limitations .................................................................... 64

5.4.2. I/O Loads and Performance .............................................................................. 66