Chapter 11 Advanced NOS Administration 11.1 Backups 11.2 Drive Mapping 11.3 Partition and Processes Management 11.4 Monitoring Resources 11.5 Analyzing.
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Chapter 11 Advanced NOS Administration
11.1 Backups
11.2 Drive Mapping
11.3 Partition and Processes Management
11.4 Monitoring Resources
11.5 Analyzing and Optimizing Network Performance
Overview of Backup Methods
• The backup process involves copying data from one computer to some other reliable storage medium for safekeeping.
• Once the data has been archived, the system administrator can then restore data to the system from any previously recorded backup.
• Considerations that are relevant for storage devices:
– Cost – Size – Manageability – Reliability
Overview of Backup Methods
• There are four types of backup procedures that define how the backup will take place:– Full - will backup everything on the hard drive at the
scheduled point in the day
– Partial - backs up selected files
– Incremental - only the files that have changed since the last backup will be selected for back up
– Differential - backs up files created or changed since the last normal or incremental backup
Installing Backup Software
• With the release of Windows 2000, the backup utility that existed with Windows NT was greatly enhanced.
• This Windows NT tool has replaced RDISK, and it is now used to back up the Registry.
• It is no longer confined to only tapes as output media, and it offers a number of other possibilities as well.
Installing Backup Software
• The Linux OS includes two utilities that can perform backups.
• They are tar and cpio. The tar utility, which is a tape archiever, combines multiple files into a single file that can be copied to the media.
• The cpio utility is used to copy in/out. • It can perform three basic actions, one of which must
be specified:– -i To extract from an archive
– -o To make a new archive– -p To print/pass (through the files)
Backup Hardware
• The most common backup hardware device used before and now is some form of magnetic tape drive.
• Tape devices are known for their long-lasting performance, which is partly due to the tape drive mechanics that some systems include.
• There are a variety of tape devices that use different tape formats for storing data.
• Many tape drives can also compress the data before it is stored on the tape.
• In most cases the compression ratio is 2:1.
Backup Hardware
• Quarter Inch Cartridge (QIC, pronounced “quick”), is a tape standard.
• Travan tape drives have a higher storage capacity than the older QIC tape drives. The most recent standard implemented on Travan tape drives was hardware compression.
Backup Hardware
• 8mm tape technology uses a tape similar to 8mm videotape and the same helical scan system used by a VCR.
• Mammoth 8mm tape technologies are an improvement on the original 8mm tape technologies with higher storage capacities and faster transfer speeds.
• AIT technology uses 8mm tapes that use the helical scan recording hardware, which is much like a VCR and have memory in the tape cartridge, known as Memory-In-Cassette (MIC).
Backup Hardware
• The Digital Audio Tape (DAT) tape standard uses 4mm digital audiotapes to store data in the Digital Data Storage (DDS) format.
• Digital Linear Tape (DLT) technology offers high capacity and relatively high-speed tape backup capabilities. DLT tapes record information on the tape in a linear format.
• Linear Tape-Open (LTO) technology comes in two distinct forms. – One is designed for high storage
capacity (Ultrium), and the other is designed for fast access (Accelis).
Backup Strategies
• There are several accepted backup strategies, and many of them are based on this popular Grandfather-Father-Son (also known as Child-Parent-Grandparent) method.
• This backup strategy uses three sets of tapes for daily, weekly, and monthly backups.
Automating Backups
• System backups should be performed at regular intervals to provide consistent data protection.
• Automation of such regularly scheduled events is an important backup consideration.
• Automation not only increases backup consistency but also gives system administrators more time to address other important network issues.
• The most common automated backup procedure consists of a system administrator inserting a tape into the drive at the end of the day.
• The system performs the regularly scheduled nightly backup of data onto the tape.
• The system administrator ejects that tape the next day and stores it for a predetermined period of time.
What is Drive Mapping?
• Drive mapping is a useful tool that allows an administrator to share resources that are stored on a server.
• The client computers that are connected to the network assign a drive letter that will act as a direct path to access those resources stored on a server over the network.
• After a user identifies a network resource to be used locally, the resource can be "mapped" as a drive.
Mapping Drives in Windows Networks
• To map a drive with Windows Explorer, navigate to the folder on the remote system in Windows Explorer by selecting Network > Neighborhood > Server name > Shared folder name.
• Another way to do this is to choose the Tools menu, and then choose Map Network Drive.
• The net use command can be used instead of mapping drives through Windows Explorer.
• net use can also be incorporated into a login script that automatically runs when the user logs in to the network.
Mapping Drives in Linux Networks
• A client computer running Linux must be mapped in a slightly different way. • Use the mount command to establish a connection to the shared directory on the
server. • Entering the syntax will map a drive to a Linux/UNIX share. • The local directory designation that points to the remote share denoted by the first
part of the command is called the directory mount point. • The mount point location must already exist before a share can be mapped to it.
mount servername:/directory/subdirectory /localdirectory
Mapping Drives in Novell Networks
• Mapping a drive to a share on a NetWare server can be done using Windows Explorer. • If the NetWare client machines are running Windows 95, 98, NT, 2000, or XP, follow the
same process for mapping drives on a Microsoft network.• A drive can be mapped at the command line by using the map command.• This map command can also be put in a login script that executes automatically as the
user logs into the network.
Using fdisk, mkfs, and fsck
• fdisk is a text-based and requires the use of one-letter commands to manipulate the options.
• type m or ? at the fdisk prompt to obtain a list of the commands that can be used.
• Once the partition changes have been made, a filesystem must be created on the partition.
• This is also referred to as formatting the partition.
• Use the mkfs utility to create a filesystem in Linux.
Using fdisk, mkfs, and fsck
• The fsck utility is used to check file systems for errors, which occur more frequently than the need to add, remove, or format partitions.
• It is a good idea to use this utility often to check for file system integrity.
Managing System Processes with cron Jobs
• The way to schedule tasks to run at regular intervals on a Linux system is with Cron Programs.
• Also known as Cron jobs, they schedule system maintenance tasks that are performed automatically.
• System Cron jobs are controled via the /etc/crontab file.
• The file begins with a set of environmental variables. These sets certain parameters for the Cron jobs such as the PATH and MAILTO
• The other lines in this file specify the minute, hour, date, month, and day of the week the job will run.
Core Dumps
• Core Dump is a recording of the memory that a program was using at the time it crashed.
• The purpose of Core Dumps is to allow programmers to study the file to figure out exactly what caused the program to crash.
Viewing Running Processes
• The processes that are currently running on a Linux system can be viewed by using the ps command.
• The ps command has a variety of options that can be used with it to manipulate its output.
• These options can be used together to display specific output using the ps command.
• There can be some considerable output that is generated when a command such as ps -a --forest is executed.
Core Dumps
• The top command functions much like the Windows 2000 Performance tool by providing detailed information regarding CPU and RAM usage.
• Sometimes a process will cause the system to lock up.
• The kill command can be used to terminate the process.
• The signal option represents the specified signal that is sent to the process.
• There are 63 different parameters that can be entered for the signal that is sent to the process.
Assigning Permissions for Processes
• Typically, programs have the same types of permission and can read the same files as the user who runs that program.
• There are certain programs that require additional permission to be run by certain users.
• Regular users cannot execute the su command because it requires root account privileges.
• Programs such as these are run using the SUID or SGID bit, which allows these programs to be run under the permission of another user.
Disk Management
• By regularly using error-checking and defragmentation programs and continually managing free disk space, the system administrator can maintain healthy hard drives.
• One preventive disk management tool available to system administrators is the use of "quotas" for user accounts.
• A quota acts as a storage ceiling that limits the amount of data each user can store on the network.
Memory Usage
• Memory diagnostic tools that allow RAM intensive applications to be discovered, and stopped if necessary, are typically built into most NOS platforms.
• System administrators can compensate for the lack of physical memory through the use of "virtual memory".
• Virtual memory allocates space on the hard drive (swap partition or file) and treats it as an extension of the system RAM.
CPU Usage
• All information used by the NOS, including the NOS itself, is processed millions of times per second by the CPU to display this information to the user.
• Built-in tools are commonly provided to allow system administrators to monitor the current level of CPU activity.
• This feedback is often presented in terms of the percentage of the CPU currently being used and is refreshed at frequent intervals.
Reviewing Daily Logs
• Most computer programs, servers, login processes, as well as the system kernel, record summaries of their activities in log files.
• These summaries can be used and reviewed for various things, including software that might be malfunctioning or attempts to break into the system.
• In Windows 2000, the Computer Management tool allows users to browse the logged events generated by the NOS.
Reviewing Daily Logs
• Linux uses log daemons to control the events that are entered in the system log.
• Most of the Linux system’s log files are located in the /var/log directory.
• The log files that are located in this directory are maintained by the system log daemon (syslogd) and the kernel log daemon (klogd).
• These two daemons are configured using the syslog.conf file.
Checking Resource Usage on Windows 2000 and Windows XP
• System resources are monitored in Windows 2000 and Windows XP with the Performance tool.
• This application is found under the Start Menu > Programs > Administrative Tools > Performance menu option.
• Users can then right-click on the graph and select Add Counters to specify which system resources to monitor in the graph.
Checking Resource Usage on Linux
• The df command is used to display the amount of disk space currently available to the various filesystems on the machine.
• When a directory name is specified, the du command returns the disk usage for both the contents of the directory and the contents of any subdirectories beneath it.
• The top command functions much like the Windows 2000 Performance tool by providing detailed information regarding CPU and RAM usage.
Key Concepts in Analyzing and Optimizing Network Performance
• The network administrator should make time to devise a proactive plan for managing the network.
• This plan enables the detection of small problems before they become large ones.
• The three key concepts in analyzing and optimizing network performance include:
– Bottlenecks – Baselines – Best practices
Bottleneck
• A bottleneck is the point in the system that limits the data throughput, which is the amount of data that can flow through the network.
• The primary performance-monitoring tool for Microsoft’s Windows 2000 Server is called Performance.
• Performance can monitor nearly all hardware and software components on a Windows 2000 server.
Bottleneck
• The various versions of the UNIX/Linux operating systems have command-line utilities that can be used to monitor performance of the UNIX/Linux network server.
• The primary tools are sar, vmstat, iostat, and ps. • The flags used by these commands can vary among
the different versions of UNIX/Linux. • Use the UNIX/Linux man command to get specifics
about the use of these commands. • The information displayed by the man command also
tells how to interpret the output generated by the command.
Baselines
• The baseline measurements should include the following statistics:– Processor, Memory, Disk
subsystem, Network queue length
• Determine how efficiently a network is performing by comparing various measurements to the same measurements taken at an earlier time.
• This point of comparison is called a baseline, which is the level of performance that is acceptable when the system is handling a typical workload.
Determining Internet Connection Speed
• The speed of a connection is limited by its lowest-speed component or the bottleneck.
• This means that even if the equipment is capable of a 50-kbps connection, the connection will be at the slower speed if the remote modem supports only 33.6-kbps.
Network Monitoring Software
• The network monitor that comes with Windows NT and Windows 2000 is a functional and useful tool for performing routine protocol analysis.
• Network Monitor can be used to display the individual frames of captured data.
• The figure shows that packets for several different protocols have been captured, including TCP, UDP, and SMB.
Network Monitoring Software
• The Sniffer products enable sophisticated filtering based on pattern matches, IP/IPX addresses, and so on.
• Sniffer Pro includes a traffic generator to assist in testing new devices or applications.
• It can be used to simulate network traffic or to measure response times and hop counts.
• Sniffer uses a dashboard-style interface.
Network Management Software
• Microsoft SMS is a high-end network management package that provides hardware and software inventory by installing the client agent on target computers.
• One of the most useful features of SMS is its software distribution feature.
• The distribution package contains the information used by SMS to coordinate the distribution of the software.
Network Management Software
• ManageWise includes an alarm/notification feature, NetWare LANalyzer agent, the management agent, Intel LANDesk Manager, Desktop Manager, and LANDesk virus protection.
• Tivoli is capable of providing a complete view of the network topology.
• Reporting tools enable customization of the view in which the data is presented, and "smart sets" can be created that group data logically.
Management Software for Small and Medium-Sized Networks
• SNMP is a protocol that is included in most implementations of TCP/IP. It has several advantages:– Simplicity, low cost, relative
ease of implementation, low overhead on the network, supported by most network hardware devices
• It uses a hierarchical database called a Management Information Base (MIB) to organize the information it gathers about the network.
Management Software for Small and Medium-Sized Networks
• Common Management Information Protocol (CMIP) was designed to improve on SNMP and expand its functionality.
• It works in much the same way as SNMP, but it has better security features.
• Also, it enables notification when specified events occur.
• Since the overhead for CMIP is considerably greater than that which is required for SNMP, it is less widely implemented.
• CMIP is based on the OSI protocol suite.
Management Service Provider (MSP)
• A new development in network management is the Management Service Provider (MSP).
• A company subscribes to an MSP service, which provides performance monitoring and network management.
• This saves the organization the cost of buying, installing, and learning to use monitoring and management software.
SNMP Concepts and Components
• There are two main parts to SNMP: 1. Management side – The management station is the centralized
location from which users can manage SNMP.
2. Agent – The agent station is the piece of equipment from which issuers are trying to extract data.
• At least one management system is needed to even be able to use the SNMP Service.
• Certain commands can be issued specifically at the management system.
SNMP Concepts and Components
• The SNMP agent is responsible for complying with the requests and responding to the SNMP manager accordingly.
• Generally, the agent is a router, server, or hub. • The agent is usually a passive component only
responding to a direct query. • In one particular instance, however, the agent is the
initiator, acting on its own without a direct query. • This special case is called a trap. • A trap is set up from the management side on the
agent.
SNMP Structure and Functions
• The data that the management system requests from an agent is contained in a Management Information Base (MIB).
• The namespace for MIB objects is hierarchical.
• It is structured in this manner so that each manageable object can be assigned a globally unique name.
• After the SNMP agent is installed, it must be configured with an SNMP community name.
• The default SNMP community name is Public.
SNMP Structure and Functions
• These three steps show what SNMP is really doing
• A community is a group of hosts running the SNMP Service to which they all belong.
• There really is no established security with SNMP. The data is not encrypted.
• Notification is possible using SNMP and will vary on an operating system–by–operating system basis.
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