exam 4 chapter 11 Flashcards
provides a convenient interface for users and applications to access computer hardware components
An operating system (OS)
is the method by which an OS stores, organizes, and manages access to files on a storage device (such as a hard drive)
A file system
File systems have the following objectives
Provide a convenient interface for users and applications to open and save files
Provide an efficient method to organize space on a drive
Provide a hierarchical filing method to store files
Provide an indexing system for fast retrieval of files
Provide secure access to files for authorized users
interacts with the file system
The user interface
on a disk drive is divided into sectors
Storage space
Storage space
Sectors are grouped to make a cluster (or block)
A Cluster is the smallest amount of space that can be occupied by a file
A disk’s cluster size is selected when the disk
is formatted
If you know that that you’re going to store many files under 2K bytes, choose
a smaller cluster size when you format
The formatting process groups sectors into
clusters and maps all disk clusters for fast access
Most file systems organize files in a hierarchy of
folders or directories
Top of the hierarchy is called the
“root”
The root often represents a
disk drive or other mass storage drive
Most file systems include an indexing system that enables users to search for a
file based on all or part of a filename
maintains a database that’s updated as files are created
The indexing system
controls (permissions) can be used to allow only authorized users to access certain files or folder
A file system’s access
can be used to secure OS files from accidental corruption or deletion
Access controls
Most current OSs include access controls except
Older DOS and Windows FAT16 and FAT 32 don’t support file and folder permissions
is a program that is loaded into memory and run by the CPU
A process
Can be an application or a program that communicates with and provides services to other processes (called a “service” in Windows and a “daemon” in Linux)
a process
allow your computer and applications to perform tasks they otherwise couldn’t
Network services
An OS can run many processes at the same time by using
multitasking
A computer multitasks by using a method called
time slicing
occurs when a CPU’s computing cycles are divided between more than one process
time slicing
Two types of multitasking
Preemptive and cooperative
preemptive
OS controls which process gets access to the CPU and for how long
OS can’t stop a process, a process maintains control until it satisfies its computing needs
Cooperative
Many applications are now designed so that different parts can be scheduled to run separately
Each part that can be scheduled to run is called
a thread
a thread
(the smallest unit of software scheduled
has two or more threads that can be scheduled separately for execution by the CPU
multithreaded application
allows performing multiple tasks or threads simultaneously, each by a different CPU or CPU core
Multiprocessing
the kernel
Schedules process to run
Making sure high-priority processes are taken care of first
Manages memory to ensure that two applications don’t attempt to use the same memory space
Makes sure I/O devices are accessed by only one process at a time
is usually shown as the layer just above the hardware
The kernel
Client OSs usually come with client software, such as
Web browsers, DNS and DHCP clients, and file-sharing clients
The main purpose of the client OS is to run applications
Which often access network resources
Most desktop computers have the following network client software
DHCP client
DNS client
HTTP client (Web browser)
File-sharing client
E-mail client
client allows the computer to access files and printers on the network
A file-sharing
intercepts the request and examines it to determine whether the resource is local (on the computer) or remote (on the network)
A redirector
With redirectors, network resources can be
accessed as though they were local
shared network folders are accessed just like a drive that is physically attached to the system
with drive mapping
In Windows, the two most common ways to access a shared resource are using the
UNC path or mapping a drive
UNC example:
\server-name\sharename\subfolder\file.extension
Using the net command example
Net use drive-letter:\server-name\sharename
The protocol used in Windows to share files and printers is
SMB, also known as Common Internet File System (CIFS)
also supports SMB implemented as an installation option called Samba
Linux
The native file-sharing protocol in the Linux environment is
Network File System (NFS)
The most common e-mail protocols
Post Office Protocol version 3 (POP3) , Simple Mail Transport Protocol (SMTP) , Internet Message Access Protocol (IMAP)
used to download incoming messages from an e-mail server to local desktops
POP3
standard protocol for sending Internet and other TCP/IP based email
Simple Mail Transport Protocol (SMTP)
has advanced message controls, including the capability to manage messages locally yet store them on a server
Internet Message Access Protocol (IMAP)
in an OS: Memory, CPU, and disk usage on client OSs is
optimized to run user applications and client network software
Most server OSs in a typical network provide:
Centralized user account and computer management
Centralized storage
Infrastructure services, such as name resolution and address assignment
Server and network fault tolerance
A server-based network is centralized management of network resources, which includes the following functions
User authentication and authorization
Account management
Security policy management
is the process of identifying who has access to the network
Most common form is a logon with a username and password
Other forms include digital certificates, smart cards, and biometric scanners
Authentication
is the process of granting or denying an authenticated user’s access to network resources
Authorization
The server version of Windows OSs includes a
centralized account management, authentication, and authorization system called Active Directory
When Active Directory is installed on a server
the server becomes a domain controller and users and computer with accounts are referred to as domain members
Accounts in Active Directory are used to distribute and enforce policies for network use and security
These policies are called
group policies
Network Information Service (NIS)
supports both Windows and Linux user authentication and authorization
Linux OSs have a basic directory service called
Lightweight Directory Access Protocol (LDAP) supports both Windows and Linux user authentication and authorization
Network storage includes
File sharing
Storing e-mail, user files, application databases, data backups and more
Many network administrators are using specialized devices to help manage their storage
Network-attached storage devices
Storage area networks
Cloud-based storage
device is a dedicated server designed solely for providing shared storage for network users
network-attached storage (NAS)
technology allows multiple servers to access a large amount of storage that appears as locally attached drives
Storage Area Network (SAN)
some or all of an organization’s data is stored on servers located offsite and maintained by a storage hosting company
Cloud-Based Storage
can be removed, replaced, or added to a server while it is running
Support for hot-swappable devices
Two or more servers configured to operate as a single unit
Server clustering
if one server fails, the other takes over
Failover cluster
spreading the workload among multiple computers
Load-balancing cluster
disk controllers capable of a disk arrangement know as redundant array of independent disks (RAID) where if one disk fails, the data is preserved and the server can continue to operate
Redundant/high-end disk systems
Most server OSs support virtual private networks (VPNs) and older dial-up method of remote access
Remote Access
Server OSs support advanced database systems such as MySQL, SQL Server, and Oracle
Database server
Corporate email systems and web-based application are examples
Client/server applications
allows multiple OSs to run on the same physical computer at the same time
Virtualization
a process that creates a software environment to emulate a computer’s hardware and BIOS
Virtualization
is the virtual environment that emulates a physical computer’s hardware and BIOS
Virtual machine
the operating system installed on a VM
Guest OS
the physical computer on which the VM software is installed
Host Computer
creates and manages VMs and creates the virtual environment in which a guest OS is installed
Virtualization software
creates and monitors the virtual hardware environment, which allows multiple VMs to share physical hardware resources
Hypervisor
runs directly on the host computer’s hardware and controls and monitors guest OSs (also called bare-metal virtualization)
Type 1 hypervisor
is installed in a general-purpose host OS and the host OS access host hardware on behalf of the guest OS (also called hosted virtualization)
Type 2 hypervisor
consists of files residing on the host computer that represent a virtual machine’s hard drive
A virtual disk
is a network configuration created by virtualization
A virtual network
is a partial copy of a VM made at a particular moment
A snapshot
Only hardware requirement is enough memory to support the host and guest OSs, adequate CPU power, and enough space to store the virtual disk
type 2 hypervisor
Has an advantage of supporting a wider variety of guest OSs because there are few incompatibility problems between the guest OS and hardware
type 2 hypervisor
Hosted Virtualization Applications
OS Training
Software Training
Application isolation
Network isolation
Software development
What-if-scenarios
Use of legacy applications
Physical-to-virtual conversion
After installed, a wizard takes you through the steps of creating a virtual machine
Using VMware Workstation
flexible networking options allowing you to configure the NIC on your VM to use of the three virtual network options or you can create your own custom virtual network
VMware Workstation
Three preconfigured options:
Bridged
NAT
Host-only
stripped down version of VMware that offers the basics of desktop virtualization
Using VMware player
Includes an option to download a virtual appliance, which is a ready-to-use VM that contains a guest OS with preconfigured applications or network services
A good option for new virtualization users and for classroom and training centers
VMware player
runs only in Windows 7 Professional, Enterprise, or Ultimate
Using Microsoft Virtual PC
it can be installed on Windows, Mac OS X, Linux, and Solaris hosts and supports a wide range of Windows, Linux, and other guest OSs
using VirtualBox
The user interface consists of a console where you can create VMs and view the status of all VMs
VirtualBox
Targeted mainly for production virtualization in data centers
Installed directly on hardware and have more stringent host machine requirements
Offer more features for managing VMs than hosted virtualization
A little more complicated to install and use as well
Type 1 hypervisor
Retire old or unreliable hardware: converting physical machines to VMs
Maintain application separation
Consolidate servers
Bare-Metal Virtualization Applications
Test installation and upgrades
Test a preconfigured application
Test what-if scenarios
Live migration
Dynamic provisioning
introduced with Windows Server 2008 and can be installed as a server role
Microsoft Hyper-V
Uses Linux as a management OS on the host
Citrix XenServer
includes VMware ESX Server, which is installed directly on the physical server without a management OS
VMware vSphere
Minimum requirement is a 1.4 GHz CPU
CPU architecture
SAS vs. SATA
Disk subsystem
Minimum requirement is 512 MB RAM
memory
suitable for businesses managing huge amounts of data, using virtualization on a large scale, running high-end applications
Datacenter Edition
suitable for most small to medium businesses
Standard Edition
aimed at small businesses with 25 or fewer users
Essentials Edition
entry-level edition, suitable for small businesses that need to purchase a complete server solution
Foundation Edition
