chapter 4_082901.pdf

Chapter 4 4. Resource Monitoring Resource monitoring is a system application that used to view information about the use of hardware (CPU, memory, disk, and network) and software resource in real time. Before you can mon...

Chapter 4 4. Resource Monitoring Resource monitoring is a system application that used to view information about the use of hardware (CPU, memory, disk, and network) and software resource in real time. Before you can monitor resources, you first have to know what resources there are to monitor. All systems have the following resources available: CPU power Bandwidth Memory Storage 4.1. System Performance Monitoring As stated above, system performance monitoring is normally done in response to a performance problem. Either the system is running too slowly, or programs (and sometimes even the entire system) fail to run at all. In either case, performance monitoring is normally done as the first and last steps of a three-step process: 1. Monitoring to identify the nature and scope of the resource shortages that are causing the performance problems 2. The data produced from monitoring is analyzed and a course of action normally resolve the problem 3. Monitoring to ensure that the performance problem has been resolved Because of this, performance monitoring tends to be relatively short-lived in duration and more detailed in scope. 4.1.1. What to Monitor? As stated earlier, the resources present in every system are CPU power, bandwidth, memory, and storage. At first glance, it would seem that monitoring would need only consist of examining these four different things. Unfortunately, it is not that simple. For example, consider a disk drive. What things might you want to know about its performance? Birana College, Department of computer Science 1  How much free space is available? How many I/O operations on average does it perform each second? How long on average does it take each I/O operation to be completed? How many of those I/O operations are reads? How many are writes? What is the average amount of data read/written with each I/O? There are more ways of studying disk drive performance; these points have only scratched the surface. The main concept to keep in mind is that there are many different types of data for each resource. The following sections explore the types of utilization information that would be helpful for each of the major resource types. 4.1.1.1. Monitoring CPU Power A CPU is generally a single microprocessor made from a wafer of semiconducting material, usually silicon, with millions of electrical components on its surface. On a higher level, the CPU is actually a number of interconnected processing units that are each responsible for one aspect of the CPU’s function. Standard CPUs contain processing units that interpret and implement software instructions, perform calculations and comparisons, make logical decisions (determining if a statement is true or false based on the rules of Boolean algebra), temporarily store information for use by another of the CPU’s processing units, keep track of the current step in the execution of the program, and allow the CPU to communicate with the rest of the computer. In its most basic form, monitoring CPU power can be no more difficult than determining if CPU utilization ever reaches 100%. If CPU utilization stays below 100%, no matter what the system is doing, there is additional processing power available for more work. However, it is a rare system that does not reach 100% CPU utilization at least some of the time. At that point it is important to examine more detailed CPU utilization data. By doing so, it becomes possible to start determining where the majority of your processing power is being consumed. 4.1.1.2. Monitoring Bandwidth Bandwidth describes the maximum data transfer rate of a network or Internet connection. It measures how much data can be sent over a specific connection in a given amount of time. For Birana College, Department of computer Science 2 example, a gigabit Ethernet connection has a bandwidth of 1,000 Mbps, (125 megabytes per second). An Internet connection via cable modem may provide 25 Mbps of bandwidth. While bandwidth is used to describe network speeds, it does not measure how fast bits of data move from one location to another. Since data packets travel over electronic or fiber-optic cables, the speed of each bit transferred is negligible. Instead, bandwidth measures how much data can flow through a specific connection at one time. Bandwidth is the primary measure of computer network speed. Virtually everyone knows the bandwidth rating of their modem or their Internet service that is prominently advertised on network products sold today. In networking, bandwidth represents the overall capacity of the connection. The greater the capacity, the more likely that better performance will result. Bandwidth is the amount of data that passes through a network connection over time as measured in bits per second (bps). Some of the more common bandwidth-related statistics are:  Bytes received/sent Network interface statistics provide an indication of the bandwidth utilization of one of the more visible buses -- the network.  Transfers per Second Normally collected for block I/O devices, such as disk and high-performance tape drives, this statistic is a good way of determining whether a particular device's bandwidth limit is being reached. Due to their electromechanical nature, disk and tape drives can only perform so many I/O operations every second; their performance degrades rapidly as this limit is reached. 4.1.1.3. Monitoring Memory Computer memory is a mechanism that stores data for use by a computer. In a computer all data consist of numbers. A computer stores a number into a specific location in memory and later fetches the value. Most memories represent data with the binary number system. In the binary number system, numbers are represented by sequences of the two binary digits 0 and 1, which are called bits. Memory capacity is usually quantified in terms of kilobytes, megabytes, and gigabytes. If there is one area where a wealth of performance statistics can be found, it is in the area of monitoring memory utilization. Due to the inherent complexity of today's demand-paged virtual Birana College, Department of computer Science 3 memory operating systems, memory utilization statistics are many and varied. It is here that the majority of a system administrator's work with resource management takes place. In any case, the following statistics are useful for monitoring storage:  Free Space Free space is probably the one resource all system administrators watch closely; it would be a rare administrator that never checks on free space (or has some automated way of doing so).  File System-Related Statistics These statistics (such as number of files/directories, average file size, etc.) provide additional detail over a single free space percentage. As such, these statistics make it possible for system administrators to configure the system to give the best performance, as the I/O load imposed by a file system full of many small files is not the same as that imposed by a file system filled with a single massive file. 4.2. File server In the client/server model, a file server is a computer responsible for the central storage and management of data files so that other computers on the same network can access the files. A file server allows users to share information over a network without having to physically transfer files by floppy diskette or some other external storage device. Any computer can be configured to be a host and act as a file server. In its simplest form, a file server may be an ordinary PC that handles requests for files and sends them over the network. In a more sophisticated network, a file server might be a dedicated network-attached storage (NAS) device that also serves as a remote hard disk drive for other computers, allowing anyone on the network to store files on it as if to their own hard drive. A file server provides a central location on your network where you can store and share files with users across your network. When users require an important file such as a project plan, they can access the file on the file server instead of having to pass the file between their separate computers. If your network users will need access to the same files and network-accessible applications, configure this computer as a file server. file server is a computer attached to a network that has the primary purpose of providing a location for shared disk access, i.e. shared storage of computer files (such as documents, sound files, photographs, movies, images, databases, etc.) that can be accessed by the workstations that Birana College, Department of computer Science 4 are attached to the same computer network. File servers generally offer some form of system security to limit access to files to specific users or groups. In modern businesses the design of file servers is complicated by competing demands for storage space, access speed, and recoverability, ease of administration, security, and budget. 4.3. Mail server Email server is software or program that can send or receive email from or to other email server. Email is electronically across the internet. For instance E-mail address of the recipient [email protected]. From this email address gmail.com indicates the domain name of the mail server which handles the recipients address and user indicates the user name of the recipient. User names and host names are separated by “@”. 4.3.1. Types of mail services Mail server can be broken down in to two main categories 1. Outgoing mail server 2. Incoming mail server Outgoing mail server is used to send mails from the sender to the receiver. SMTP is one of the mail type of outgoing mail server. Incoming email server is used to receive mail messages from the sender. POP3 and IMAP are the mail type of email server that used to receive emails. SMTP (simple mail transfer protocol) ❖ Simple Mail Transfer Protocol (SMTP) is the standard protocol for sending emails across the Internet. ❖ SMTP uses TCP port 25 or 2525 IMAP (Internet Mail Access Protocol) and POP3 (Post Office Protocol) ❖ Both used to receive email from the sender. ❖ POP3 is used for storing sent and received messages on PCs local hard drives. ❖ IMAP is always used to store copies of messages on servers. ❖ Main differences between IMAP and POP3: Birana College, Department of computer Science 5  ✓ POP3 protocol assumes there is only one client connected to the mailbox ✓ IMAP protocol allows simultaneous access by multiple clients, so it is suitable if the mailbox is used by multiple users. 4.4. Remote Administration Services Remote administration is any method of controlling a computer from a remote location. Remote administration of computer is increasingly common because of the significant cost benefit, many tasks can be automated and the administrator does not have to physically limit each computer. Remote control software’s provides has the ability to login and access computers remotely. The remote administrator software allows you to take control of LAN, WAN, so you can see the remote computers screen on your monitor and all your mouse movement. Utilizing remote control software enables: Personnel to transfer files and folders quickly and easily. Communicate by instant message Example of remote administration tools are GoToMypc, PcAnywhere and RemotelyAnywhere. Common tasks for which remote administration is used: 1. General: controlling one’s own computer from a remote location. For instance, access the software on a personal computer from an internet café. 2. Shutdown: is the process for shutting or rebooting another computer over a network. 3. Accessing peripherals: it is possible to access network resources like printer remotely and retrieving data from the network. 4. Modifying: remote administrators can make editing another computer registry setting, modifying system services, installing software on another machine, modifying logical groups and resetting passwords. 5. Viewing: like remotely assisting others or supervising computers. 4.5. Network Printing Network printing is the collection of software components in Windows Server 2008 that provide network printing services for client computers. In some small offices, it might be practical to have a printer attached to every computer, but in an organization consisting of more than a few computers, sharing printing resources is desirable. The printer can be connected to the print server through internal network adapters, external network adapters, or another server. Birana College, Department of computer Science 6  ❖ Network administrators must manage network printing, printer availability, and printer security ❖ A shared printer is an object that can be shared with other network users ❖ Print devices ❖ Can be attached to servers or client workstations ❖ Can connect directly to the network with no attached computer ❖ A print device can be accessed through a print server ❖ Using a local print device ❖ Using network print devices ❖ The principal distinction between network printers and local printers, in Microsoft terminology, is where the spooling takes place ❖ Local printers spool to a location on the local hard disk ❖ Network printers spool to a location on the network print server 4.5.1. Installing a Network Printer Creating a network printer ❖ Install the printer locally on the computer that is to become the print server ❖ Share the printer to make it accessible to users over the network ❖ Connect the print device to the local print server ❖ Install the printer software (the printer) ❖ To install local printers, use the Add Printer Wizard on your local computer 4.5.2. Controlling Access to Printers ❖ For security reasons, you may decide to restrict certain types of printer usage to certain users ❖ Printer permissions ❖ Restrict who can print to a printer ❖ Restrict who can manage a printer ❖ Restrict who can manage the documents sent to a printer Birana College, Department of computer Science 7  ❖ Printer permissions are assigned on the Security tab in the printer’s Properties dialog box 4.5.3. Understand Network Printing Concepts The network should be configured for sharing printers to enable network printing. Local printer, shared printer, and network printer are the three basic printing configurations used while designing a network and configuring printers. Basic printing configurations for networked computers 4.5.3.1. Local Print Devices A printer is referred to as the print device, and is used for providing printed outputs. It is essential to install the necessary drivers to ensure proper working of the print device. Software called printer is required to control the printing process. The printer determines where and when the output should be sent. Local print devices provide the most convenient way of printing from a workstation computer. 4.5.3.2. Shared Print Devices Sharing a locally attached printer. Sharing print devices directly connected to the network. Sharing a Locally Attached Printer Repeated interruptions by multiple users may affect the productivity of the user. There is a reduction in speed and response time, since the computer’s resources are used for providing the required output for multiple users. Sharing Print Devices Directly Connected to the Network Print devices connected to the network have their own internal network interface card that provides network identification to the device. Print devices are generally configured on a centralized network to provide convenient access to multiple users. Sharing of print devices decreases the purchase, installation, and maintenance cost of the printer. Birana College, Department of computer Science 8 The following information has to be provided while installing a network-capable print device: ✓ The print device’s IP address. ✓ The print device’s manufacturer and printer type. ✓ A share name for the print device. How can I share a printer between multiple computers? Users who have multiple computers in their home or work environment may wish to share a printer with the other computers to help save on cost and for convenience. Below are some of the ways you can share a printer on a network for different setups. Before setting up the printer to be shared on a network, you must decide what setup you plan on doing. Below are the different setups and their advantages and disadvantages. Printer connected to computer or server Connecting a printer to a computer and sharing the printer from that computer is the most common solution for sharing a printer because of the ease and price. The primary disadvantage of this is that the computer must always be on in order for the printer to work. Although this solution may not be the best solution for everyone it is usually the easiest and cheapest solution for sharing your printer between all the computers on your network. 4.5.3.3. Network printer Some printers, often high-end printers have the capability to connect directly to a network or have hardware installed into them that enables the printer to be connected to the Network. If your printer supports this option and has the necessary hardware you should be able to connect the printer directly to the Network and have it detected by the computers. When these printers are connected to a network you'll often be required to enter the network information such as the networks gateway, printer IP, etc. 4.6. Permissions Permission is the type of access granted to a user, group, or computer to access resources. Permission can be applied to resources such files, folders and printers like privilege to read a file, delete a file, or to create a new file in folder. Birana College, Department of computer Science 9  4.6.1. Types of permission Security level permission Share level permissions 4.6.1.1. Security level permission ✓ Security or permission can set on drives, folders and files. ✓ By default, security permissions will be inherited from its parent drive or folder. ✓ Creators of files and folders are owners. ✓ Security permissions include : full control, read and execute, modify, write, read, and list folder contents 4.6.1.2. Share level permission ✓ Can be set on drives and shared folders but not files. ✓ Shared folders can be accessed from networks. ✓ Share permissions include, reader, owners and contributors. Birana College, Department of computer Science 10