Understanding Network Operating Systems and Servers

1. CEG 2400 FALL 2012Network Operating Systems

2. Characteristics of Network Operating Systems (NOS) • Client/Server type architecture • NOS do the following: • Server enables multiple clients to share resources managed by the NOS • Centrally manage network resources, such as programs, data, and devices (for example, printers). • Secure access to a network. • Allow remote users to connect to a network. • Allow users to connect to other networks (for example, the Internet).

3. Characteristics of Network Operating Systems • NOS do the following:(con’t) • Back up data and make sure it's always available • Allow for simple additions of clients and resources • Monitor the status and functionality of network elements. • Distribute programs and software updates to clients. • Ensure efficient use of a server's capabilities. • Provide fault tolerance in case of a hardware or software problem. • Not all of these functions are built in to every NOS installation; some are optional.

4. Network Operating Systems and Servers • Determining optimal server hardware • Questions to ask • What kinds of applications will run on the server? • How many clients will connect to the server? • How much storage space will each user need? • How much downtime, if any, is acceptable? • What can the organization afford?

5. Network Operating Systems and Servers • Determining optimal server hardware (cont’d.) • Applications influence: • Type of application • Resources used • Processing burden • Vendor reputation - High quality, dependability, excellent technical support • Server Reliability • Spend as much as necessary • Component failure: widespread effects, costs

6. Client Support • Very important NOS function • Allows efficient communication, resource sharing • NOS client support tasks include: • Creating and managing client accounts • Enabling clients to connect to the network • Allowing clients to share resources • Managing clients’ access to shared resources • Facilitating communication between clients

7. Client/Server Communication Process • Logon process – Both client and server software • Redirector - Client • Intercepts requests, determines where to send • The server’s OS, clients’ OSs, and redirectors must be compatible for a multivendor environment to succeed • File Access Protocol - Server • Windows client communication with Windows Server 2008 • CIFS (Common Internet File System) • Older protocol SMB (Server Message Block) • Broad support allows every client type to authenticate, access resources (Mac, Linux, etc)

8. A client connecting to an NOS Client/Server Communication

9. Client/Server Communication • Middleware Software • Translates requests, responses between different types of clients and the server • A 3-tier architecture • Client/server environment incorporating middleware

10. Users and Groups • After NOS client authentication • Client gains access to NOS services, resources • Start with none • Administrator account • Most privileged user account • Unlimited rights to server, domain resources, objects • Created by default • Administrator - Windows • Root on UNIX or Linux systems • Admin - Netware

11. Users and Groups Access Rights • User names • NOS grants each network user access to files and other shared resources • Groups • Basis for resource and account management • Greatly assists in resource sharing and security control

12. Groups • Nesting or hierarchical group arrangement • Simplifies management • Group arrangement • Affects permissions granted to each group’s members • Inherited permissions • Passed down from parent group to child group • After user, group restrictions applied • Client allowed to share network resources

13. Sharing Applications • Shared applications • Specifically designed to run applications on file server • Application licensing types • Per user licensing – number of active users • Per seat licensing – number of potential users • Site license – unlimited users

14. Sharing Applications • Installing application on server • Purchase appropriate type and number of licenses • Verify server resources • Install application • Make application available to users • NOS responsible for arbitrating file access • Problem with shared file access • Multiple users simultaneously accessing same data files, same program files

15. Sharing Printers • Increases resource management efficiency; reduces costs • Print server • Manages print services • All NOSs perform common tasks in managing printers • Client redirector • Determines where print request should transmitted • Network, workstation

16. Shared printers on a network Sharing Printers

17. Memory • Physical memory: RAM chips • Virtual memory: stored on hard drive • Page file (paging file, swap file) • Managed by operating system • Paging • Moving blocks (pages) from RAM into virtual memory • Virtual memory can boost total memory available

18. Memory • Virtual memory advantages • Easily expands memory available to server applications • Engaged by default • Virtual memory disadvantage • Slows operations • Hard drive access much slower versus physical memory access

19. Memory Model • Addressing schemes • 32-bit addressing scheme (4 G limit) • 64-bit addressing scheme (18 exabytes – big number) • NOS assigns each application (process) • Own 32-bit memory area • Logical subdivision of memory available to server

20. Multitasking • Execution of multiple tasks at one time • All operating system perform this • Does not mean performing more than one operation simultaneously • Preemptive multitasking • Happens quickly • Appearance of tasks occurring simultaneously • Time sharing: UNIX • Windows also does it • Run, stop, put process state in memory, next task

21. Multiprocessing • Process • Routine of sequential instructions that runs until goal is achieved • Thread • Self-contained; well-defined task within process • Main thread • All processes have one • One processor systems • One thread handled at any time

22. Multiprocessing NOS • Support use of multiple processors to handle multiple threads • Technique to improve response time • Splits tasks among more than one processor • Expedites single instruction completion

23. Multiprocessing • 1. Symmetric multiprocessing* • Splits all operations equally among two or more processors • 2. Asymmetric multiprocessing • Assigns each subtask (thread) to specific processor • Multiprocessing is an advantage to servers with high processor usage • Speed • Run numerous tasks simultaneously • Almost all NOSes do multiprocessing

24. File System • File system • Method of organizing, managing, and accessing files • Through logical structures, software routines • Windows - NTFS (New Technology File System) • Netware – NSS • Solaris - UFS (UNIX file system) • Linux native file system type • ext4: “fourth extended” file system (NFS, Samba) • Disk data distribution • Difference is how they set up the file structure

25. Summary • Characteristics common to all NOS • Systems and servers, client support, identifying and organizing network elements, sharing applications and printers, memory, processing modes, managing system resources

26. Misc • Pacemaker hack can deliver deadly 830-volt jolt • Pacemakers and implantable cardioverter-defibrillators could be manipulated for an anonymous assassination • Pacemakers from several manufacturers can be commanded to deliver a deadly, 830-volt shock from someone on a laptop up to 50 feet away, the result of poor software programming by medical device companies. • The trend is now to go wireless. Several medical manufacturers are now selling bedside transmitters that replace the wand and have a wireless range of up to 30 to 50 feet.

27. End of Network Operating Systems Questions