1. Goals By Tariku Ahmed

2.  An operating system is a program that manages computer hardwires. **  In other words  OS resides on the computer hardware  Acts as the boss of everything that goes on the computer above the BIOS  Manages in what order things get processed using a predefined algorithm  Translates communication signals between the hardware and the application program/user.

3. DOS (3)DOS (3) Symbian OS (18)Symbian OS (18)  Windows 95 / 98 / Me /Windows 95 / 98 / Me / DOS (24)DOS (24) IBM (8)IBM (8) UNIX (65)UNIX (65) Windows NT (89)Windows NT (89) Linux OS (249)Linux OS (249) Virtualization (69)Virtualization (69) Windows Server 2003 (81)Windows Server 2003 (81) Macintosh (104) Macintosh (104) VMS (10) VMS (10) Windows Server 2008 (52)Windows Server 2008 (52) Other (33)Other (33) Windows 2000Windows 2000 Professional (24)Professional (24) Windows Vista (46)Windows Vista (46) Palm OS (16)Palm OS (16) Windows 2000 Server (67) Windows XP (73)Windows XP (73) Sun Solaris (16) Sun Solaris (16) Windows 7 (31)Windows 7 (31)

4. Distributed Operating Systems & Algorithms, by Randy Chow and Theodore Johnson, 1997. ◦ The integration of  Services  Multiple computer system  Distributed resource  Distributed controls

5.  There are two parties who have a vested interest on Distributed Operating System. ◦ System service provider ◦ User ◦ Example of things that we use every day which employee Distributed System  On demand Movie, Turbo Tax, Satellite navigation systems (GPS)

6.  Both the user and system provider are interested on having a system with following characteristics. 1.Efficiency 2.Flexibility 3.Consistency 4.Robustness

7.  Effective Business Recovery ◦ Effective data recovery ◦ Effective error handling  Effective distributed system ◦ Load sharing, balanced and overlapped communication  Effective networking ◦ Avoid bottle neck ◦ Redundancy in physical communication ◦ Up to date communication system ◦ Multiprocessing and multitasking

8.  No time constraint  No hardware dependency  Wide area coverage  Friendliness ◦ Easy and direct forward user interface with GUI ◦ Minimal training  Easy retrieval

9. Major issues ◦ Lack of global information ◦ Potential replication  Synchronized software update ◦ Example: tax software  Predictable software behavior  Effective Business Recovery ◦ Effective data recovery ◦ Effective error handling

10.  Employee auto correcting/ programs with high fault tolerance ◦ Database availability error – wait a couple of seconds and resubmit ◦ Network error – reroute with the redundant line ◦ Notify customer – about outstanding issues and give an accurate or educated guess recovery time.

11.  Distributed Operating Systems & Algorithms, by Randy Chow and Theodore Johnson, 1997.  Abraham Silberschatz (2005) Operating System Concepts 7 th edition. TCP/IP and Distributed System by Vivek AcharyaVivek Acharya