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 CDROM with the NT server software and it is found
on the web site: www.microsoft.com/hcl
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
60th 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