Chapter 8 Windows NT

The Major Network Operating Systems Windows NT Server Windows 2000 Server Novell Netware UNIX Many LANs include a mix of all of the above network operating systems

Questions to ask when selecting a Network Operating System Is it compatible with existing infrastructure? Will it provide the security that is required? Can the technical staff manage the system? Will the NOS support our current application programs? Will it accommodate future growth? Will it support future services we will require? Can we afford it? What kind of technical support can we get?

Items to consider when selecting the server hardware How many clients will be on the server? What kind of applications will run on the server? How much storage space will ech user need? How much down time is acceptable? What can you afford?

Multiprocessing The processing load is divided across several CPUs Windows NT uses symmetric multiprocessing, a technique in which the total processor load is split evenly among the processors Simplier operating systems use asymmetric processing where, for example, all operating system tasks are on one processor and all user tasks are on the remaining processors NT with two processors generally runs at about 150 percent of the speed of a one-processor system

Multiprocessing – Continued Multiprocessing offers a great advantage to servers that perform numerous taks simultaneously If the server is used only for file and print sharing, multiple processors will not speed up the process much Other resources may cause a bottleneck – access time for hard drive as an example

Windows NT Commercially released in 1993 Was written from scratch in the late 1980s First NOS based entirely on a GUI Made network administration easier Provides for a client-server based network operating system Uses the same interface as found in Windows 95/98 Provides excellent file security Supports symmetric multiprocessing Supports preemptive multitasking (see webopedia)

Where did Windows NT come from? In the late 1980s, Microsoft and IBM collaborated on a replacement for DOS on Intel computers Their new OS was called OS/2 Microsoft recognized the need for a more advanced OS with the ability to run on other microprocessors. Microsoft hired Dave Cutler to lead the development of a new OS written in C (called OS/2 NT) so that it would be portable to other microprocessors In 1990 Microsoft released Windows 3.0 which became very popular

History of NT continued Microsoft and IBM disagreed as to how to market OS/2 and Windows Microsoft wanted to expand capabilities of Windows to compete with OS/2 When cooperation failed, IBM retained the OS/2 system and Microsoft changed the name of the OS/2 NT project to windows NT

NT Server 4.0 Minimum Required Hardware (p. 324) Processor: Intel 486 Memory: 16 MB RAM Hard Disk: 110 MB Microsoft’s Hardware Compatibility List lists all computer components proven to be compatible with Windows NT server. This list is on the CD- ROM with the NT server software and it is found on the web site:

NT Server’s Memory Model Uses 32-bit addressing scheme (Windows 2000 server supports 64-bit addressing) Each application is assigned its memory area so that the running processes are less prone to interfering with each other’s operations Supports virtual memory – space on the hard drive that is reserved to be used to make it appear as though there is more main memory available A process can temporarily use virtual memory when it needs more memory that the physical memory can provide To find out how much virtual memory your system is using: Control Panel, System, Performance, Change

NT File Systems NT supports HPFS, FAT, NTFS, and CDFS Typically, you will use NTFS

FAT Stands for File Allocation Table Original file system designed in the 1970s to support floppy disks and hard disks Disk surface is divided into clusters A number of clusters go into making a partition The FAT table is a hidden file found at the beginning of the partition that keeps track of used and unused allocation units on the partittion FAT is inadequate for most server operating systems –Partition size limitation, fragmentation, and naming limits

FAT Continued FAT partition cannot be larger than 4 GB FAT uses 16-bit fields to store file information File names can have at most 8 characters in the name The filke attributes available are: Read, Write, System, or Hidden FAT files cannot use NT security Data is stored in non-contiguous blocks Can convert from FAT to NTFS on an NT server

FAT 32 File System FAT was enhanced to accommodate long file names Uses 32-bit addressing for faster data access Cannot take advantage of NT’s security and file compression

HPFS High-Performance File System Designed for the OS/2 operating system Data is organized into contiguous blocks Rarely found installed on an NT server

NTFS New Technology file System Part of NT Workstation and NT Server Filenames up to 256 characters long File size information stored in 64-bit fields Supports large files (16 exabytes(2 to the 60 th power))

NT Domains A logical grouping of users, servers, and other network resources A Microsoft concept A company may break its LAN up into multiple domains A domain must have a Primary Domain Controller (PDC) that keeps track of resources, users,and privileges A domain can only have one PDC You may have a Backup Domain Controller (BDC)

NT Domains – Continued If a PDC goes down, a BDC may be promoted to function as the PDC The domain may have any number of member servers- takes no role in managing accounts and security A member server usually runs one or more application programs A server in a domain must be a PDC, a BDC, or a member server

Trust Relationship between Domains A trust relationship between two domains allows users in one domain to use resources in the other domain Several types of trust relationships –One-way trust –Multiple one-way trust –Two-way trust

One-Way Trust Involves two domains: A and B Users in Domain B are allowed to access resources in Domain A (see Fig. 8-3, p.331) The Domain A with the resources to share trusts the domain B with the users that want access to the resources. The domain with the resources to share is called the Trusting Domain The domain that contains the users is called the Trusted Domain An arrow is drawn from the Trusting Domain and pointing to the Trusted Domain

Multiple One-Way Trusts Network consists of multiple one-way trusts One Trusted Domain and several Trusting Domains See Fig. 8-4, p. 332

Two-Way Trust Users from Domain A can access resources in Domain B Users in Domain B can access resources in Domain A Common in WAN situations where two or more locations manage their own domains,but need to share information See Figure 8-5, p. 333

Accessing Resources in a Trusting Domain After the trust relationship has been established, users with accounts in the Trusted Domain can be given permissions to resources in the Trusting Domain Trust relationships are established through Start, Programs, Administrative Tools, User Manager for Domains, Policies, Trust Relationships Trust relationships can be broken after they are created

Domain Models with Trust Relationships Single Domain Model Master Domain Model Multiple Master Domain Model Complete Trust Domain Model

Single Domain Model Simplest domain model All users and resources are in one domain See Figure 8-6 Note – This is the model we are using for installation of NT server software

Master Domain Model See Figure 8-7, p. 335 One Trusted domain (master) used to maintain all information on user accounts Multiple Trusting domains that contains resources Resources are separated by logical groupings

Multiple Master Domain Model Two or more master domains that are joined in a two-way trust See Figure 8-8, p. 336 Users in a multiple master domain can log on to a single master domain and then use resources from several different resource domains

Complete Trust Domain Model Bunch of Single Domains, each of which has a two-way trust between every other Domain See Figure 8-9, p. 337

Synchronization A PDC informs a BDC that it needs to update its user account information database The update might include new users or groups, new or changed passwords, or new or changed group memberships. On large networks with several BDCs,this communication could take up a lot of bandwidth To minimize the effect, the synchronization between the PDC and the BDCs are staggered Network administrator can force synchronization from Service Manager under Administrative Tools

Forced Synchronization Two types: partial and full Partial – only modifications to user account information are transmitted to the other domain controllers Full – Entire user account database is copied to the BDC Why you you need to force synchronization when this is done automatically and on a regular basis? See p. 340 for the answer.

Browser A browser service is used to keep track of all shared resources in the network The browser compiles a database of these resources. The browser tracks the location, the availability, and the name of shared resources Types of browsers –Domain master browser – tracks resources for a group of domains –Master browser – tracks shared resources for its domain –Backup browser – keeps a copy of the master browser’s database in case master browser goes down

Browser – Continued Every time a computer on the network starts, it registers with the domain’s master browser. If there is more than one domain, each master browser passes along its browse list to the domain master browser By default, the PDC is the master browser for its domain