Chapter 14 Study Guide - Revision history

Powe0122 at 03:47, 25 April 2012

2012-04-25T03:47:34Z

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	~~'''~~TROUBLESHOOTING, PERFORMANCE, SECURITY~~'''~~		===TROUBLESHOOTING, PERFORMANCE, SECURITY===

	~~'''~~Troubleshooting Methodology~~'''~~		===Troubleshooting Methodology===
	*Proactive Maintenance		*Proactive Maintenance
	Taking the necessary steps to minimize future problems		Taking the necessary steps to minimize future problems
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	Always document the solution to help quickly resolve future problems		Always document the solution to help quickly resolve future problems

	~~'''~~Troubleshooting Procedures~~'''~~		===Troubleshooting Procedures===
	*Gather as much information as possible		*Gather as much information as possible
	System log files		System log files
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	A short term solution might fail in the long term because of an underlying problem		A short term solution might fail in the long term because of an underlying problem

	~~'''~~Hardware Related Problems~~'''~~		===Hardware Related Problems===
	*Can come from damaged hardware or improper hardware or software configuration		*Can come from damaged hardware or improper hardware or software configuration
	*Using the dmesg command or viewing the /var/log/boot.log and var/log/messages files can isolate most hardware problems		*Using the dmesg command or viewing the /var/log/boot.log and var/log/messages files can isolate most hardware problems
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	*Hard drives are the most common hardware component to fail		*Hard drives are the most common hardware component to fail

	~~'''Software~~ Related Problems~~'''~~		===software Related Problems===
	*Can be application or OS related		*Can be application or OS related
	*Application Related Problems		*Application Related Problems
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	The ulimit command can be used to increase the number of processes the user can start in a shell		The ulimit command can be used to increase the number of processes the user can start in a shell

	*Operating System Related Problems		===Operating System Related Problems===
	Typically include problems with X windows, boot loaders, and filesystems		Typically include problems with X windows, boot loaders, and filesystems
	Use xwininfo or xdpyinfo commands to attemp to isolate problems with X windows		Use xwininfo or xdpyinfo commands to attemp to isolate problems with X windows
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	Corrupted filesystems can be identified by very slow write requests, errors printed to the console, or failure to mount		Corrupted filesystems can be identified by very slow write requests, errors printed to the console, or failure to mount

	~~'''~~User Interface Related Problems~~'''~~		===User Interface Related Problems===
	*Users need to understand how to use their desktop environment, but often will not		*Users need to understand how to use their desktop environment, but often will not
	*Assistive technologies are tools you can use to modify your desktop experience		*Assistive technologies are tools you can use to modify your desktop experience
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	~~'''~~Linux Performance~~'''~~		===Linux Performance===

	Monitor system performance using command-line included in the sysstat package.		Monitor system performance using command-line included in the sysstat package.
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	Keep CD and DVD drives on a separate hard disk controller		Keep CD and DVD drives on a separate hard disk controller

	~~'''~~Monitoring Performance with sysstat Utilities~~'''~~		===Monitoring Performance with sysstat Utilities===

	Using information from the /proc directory and system devices, the System Statistics (sysstat) package contains utilities that monitor the system.		Using information from the /proc directory and system devices, the System Statistics (sysstat) package contains utilities that monitor the system.
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	*sar -u 1 3 Displays real time CPU usage every 1 second for 3 times.		*sar -u 1 3 Displays real time CPU usage every 1 second for 3 times.

	~~'''~~Other Performance Monitoring Utilities~~'''~~		===Other Performance Monitoring Utilities===

	*top utility (discussed in Chapter 9)		*top utility (discussed in Chapter 9)
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	~~'''~~Security~~'''~~		===Security===
	'''Locking enviorment'''		'''Locking enviorment'''

Powe0122 at 03:41, 25 April 2012

2012-04-25T03:41:18Z

@@ Line 1: / Line 1: @@
 '''Troubleshooting Methodology'''
 *Proactive Maintenance
@@ Line 162: / Line 164: @@
 *free command can be used to display the total amounts of physical and swap memory (in Kilobytes) and their utilizations.
 *vmstat command indicates more information than the free command to indicate whether more physical memory is required.

Powe0122 at 03:32, 25 April 2012

2012-04-25T03:32:57Z

← Older revision		Revision as of 03:32, 25 April 2012
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			'''Troubleshooting Methodology'''
			*Proactive Maintenance
			Taking the necessary steps to minimize future problems
			Includes performing system back-ups and identifying potential problem areas.
			*Reactive Maintenance
			Correcting problems when they arise
			Always document the solution to help quickly resolve future problems

			'''Troubleshooting Procedures'''
			*Gather as much information as possible
			System log files
			Run information utilities such as ps or mount
			“tail –f /path/to/logfile” opens a log file for continuous viewing
			*Isolate the problem
			Determine if the problem is persistent, intermittent, and how many users are effected
			*List possible causes and solutions
			google is your best friend
			*Implement and test solution
			*Document your solution and process

			*Prioritize problems
			Solve most severe problems first
			Spending too much time on small problems can result in reduced productivity
			*Try to solve the root of the problem
			A short term solution might fail in the long term because of an underlying problem

			'''Hardware Related Problems'''
			*Can come from damaged hardware or improper hardware or software configuration
			*Using the dmesg command or viewing the /var/log/boot.log and var/log/messages files can isolate most hardware problems
			*The absence of or improper drivers prevents the OS from using the associated hardware
			Use lsusb to view only usb devices
			Use lspci to view only PCI devices
			*Lsmod command lists the drivers loaded into the kernel
			By comparing the output of dmesg, lsusb, and lspci with the lsmod output, you can determine if a driver is missing
			*Hard drives are the most common hardware component to fail

			'''Software Related Problems'''
			*Can be application or OS related
			*Application Related Problems
			Can fail during execution due to missing program libraries and files, process restrictions, or conflicting applications
			Identify missing files in a package by using the –V option with the rpm command
			Use the ldd command to identify which shared libraries are required by certain programs
			It is good practice to run the ldconfig command to ensure the shared library directories are updated
			The ulimit command can be used to increase the number of processes the user can start in a shell

			*Operating System Related Problems
			Typically include problems with X windows, boot loaders, and filesystems
			Use xwininfo or xdpyinfo commands to attemp to isolate problems with X windows
			Placing the word “linear” and removing “compact” from the /etc/lilo.conf file often fixes LILO boot loader problems
			The GRUB boot loader errors are typically the result of a missing file in the /boot directory
			File systems can become corrupted due to high use accessing the hard drive
			Corrupted filesystems can be identified by very slow write requests, errors printed to the console, or failure to mount

			'''User Interface Related Problems'''
			*Users need to understand how to use their desktop environment, but often will not
			*Assistive technologies are tools you can use to modify your desktop experience
			Accessed by opening the system menu and navigate to preferences, assistive technologies


	'''Linux Performance'''		'''Linux Performance'''

Powe0122 at 02:07, 11 April 2012

2012-04-11T02:07:49Z

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	'''Common options with the sar caommand'''		'''Common options with the sar caommand'''

	CPU Usage of ALL CPUs (sar -u) Default		*CPU Usage of ALL CPUs (sar -u) Default
	CPU Usage of Individual CPU or Core (sar -P)		*CPU Usage of Individual CPU or Core (sar -P)
	Memory Free and Used (sar -r)		*Memory Free and Used (sar -r)
	Display swapping statistics (sar -W)		*Display swapping statistics (sar -W)
	Reports run queue and load average (sar -q)		*Reports run queue and load average (sar -q)
	sar -u 1 3 Displays real time CPU usage every 1 second for 3 times.		*sar -u 1 3 Displays real time CPU usage every 1 second for 3 times.

	'''Other Performance Monitoring Utilities'''		'''Other Performance Monitoring Utilities'''

Powe0122 at 01:54, 11 April 2012

2012-04-11T01:54:20Z

← Older revision		Revision as of 01:54, 11 April 2012
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	Limited in abilities		Limited in abilities

	~~[[File:Example.jpg]]~~

	'''Examining the Output of the mpstat command'''		'''Examining the Output of the mpstat command'''

Powe0122 at 01:51, 11 April 2012

2012-04-11T01:51:14Z

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	Example: mpstat –P 0 would display the first processor on the system.		Example: mpstat –P 0 would display the first processor on the system.
	Limited in abilities		Limited in abilities

			[[File:Example.jpg]]

	'''Examining the Output of the mpstat command'''		'''Examining the Output of the mpstat command'''

Powe0122 at 01:49, 11 April 2012

2012-04-11T01:49:02Z

← Older revision		Revision as of 01:49, 11 April 2012
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	'''Examining the Output of the mpstat command'''		'''Examining the Output of the mpstat command'''

	%user= % of time the processor spent executing user programs and daemons		*%user= % of time the processor spent executing user programs and daemons
	%nice= % of time the processor spent executing programs and daemons that had nondefault nice values		*%nice= % of time the processor spent executing programs and daemons that had nondefault nice values
	%sys= % of time the processor spent maintaining itself		*%sys= % of time the processor spent maintaining itself
	%iowait= % of time the CPU was idle when an outstanding disk I/O request existed.		*%iowait= % of time the CPU was idle when an outstanding disk I/O request existed.
	%irq= % of time the CPU is using to respond to normal interrupts that span multiple CPUs.		*%irq= % of time the CPU is using to respond to normal interrupts that span multiple CPUs.
	%soft= % of time the CPU is using to respond to normal interrupts that span multiple CPUs		*%soft= % of time the CPU is using to respond to normal interrupts that span multiple CPUs
	%steal= % of time the CPU is waiting to respond to virtual CPU requests		*%steal= % of time the CPU is waiting to respond to virtual CPU requests
	%guest= % of time the CPU is executing another virtual CPU		*%guest= % of time the CPU is executing another virtual CPU
	%idle= % of time the CPU did not spend executing tasks. Should be greater than 25% over a long period of time.		*%idle= % of time the CPU did not spend executing tasks. Should be greater than 25% over a long period of time.

	'''iostat (input/output statistics)'''		'''iostat (input/output statistics)'''

Powe0122 at 01:47, 11 April 2012

2012-04-11T01:47:33Z

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	Monitor system performance using command-line included in the sysstat package.		Monitor system performance using command-line included in the sysstat package.
	To make it easier to identify performance problems, a network administrator should run performance utilities on healthy Linux systems to develop a baseline.		To make it easier to identify performance problems, a network administrator should run performance utilities on healthy Linux systems to develop a baseline.
	Performance Problems:
	Software		'''Performance Problems:'''
	Hardware		*Software
	Combination of the two		*Hardware
			*Combination of the two

	'''Software Problems'''		'''Software Problems'''

Powe0122 at 01:46, 11 April 2012

2012-04-11T01:46:31Z

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	'''Other Performance Monitoring Utilities'''		'''Other Performance Monitoring Utilities'''

	top utility (discussed in Chapter 9)		*top utility (discussed in Chapter 9)
	free command can be used to display the total amounts of physical and swap memory (in Kilobytes) and their utilizations.		*free command can be used to display the total amounts of physical and swap memory (in Kilobytes) and their utilizations.
	vmstat command indicates more information than the free command to indicate whether more physical memory is required.		*vmstat command indicates more information than the free command to indicate whether more physical memory is required.

Powe0122 at 01:45, 11 April 2012

2012-04-11T01:45:50Z

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	'''Software Problems'''		'''Software Problems'''

	Software that requires too many system resources may use CPU, memory, and peripheral devices creating poor performance.		Software that requires too many system resources may use CPU, memory, and peripheral devices creating poor performance.
	Too many processes running or rouge processes		Too many processes running or rouge processes

	'''Hardware Problems'''		'''Hardware Problems'''

	Improperly configured hardware (May still Work)		Improperly configured hardware (May still Work)
	Old ( Most companies retire computer equipment after two to five years of use)		Old ( Most companies retire computer equipment after two to five years of use)
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	'''Resolutions'''		'''Resolutions'''

	Software problems can sometimes be resolved by changing hardware.		Software problems can sometimes be resolved by changing hardware.
	Move or Remove the software		Move or Remove the software
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	'''Monitoring Performance with sysstat Utilities'''		'''Monitoring Performance with sysstat Utilities'''

	Using information from the /proc directory and system devices, the System Statistics (sysstat) package contains utilities that monitor the system.		Using information from the /proc directory and system devices, the System Statistics (sysstat) package contains utilities that monitor the system.
	To install the latest version of sysstat on a Linux system, use the following method:		To install the latest version of sysstat on a Linux system, use the following method:
	1. yum install sysstat		1. yum install sysstat

	'''Three of the System Statistics (sysstat) package performance monitoring utilities include:'''mpstat (multiple processor statistics) command		'''Three of the System Statistics (sysstat) package performance monitoring utilities include:'''
	iostat (input/output statistics)		*mpstat (multiple processor statistics) command
	sar (system activity reported) command		*iostat (input/output statistics)
			*sar (system activity reported) command

	'''mpstat (multiple processor statistics)'''		'''mpstat (multiple processor statistics)'''

	Used to monitor CPU performance for all processors on the system since the system was started or rebooted.		Used to monitor CPU performance for all processors on the system since the system was started or rebooted.

	''To monitor a single cpu use the –P option followed by the processor number.''		''To monitor a single cpu use the –P option followed by the processor number.''

	Example: mpstat –P 0 would display the first processor on the system.		Example: mpstat –P 0 would display the first processor on the system.
	Limited in abilities		Limited in abilities

	'''Examining the Output of the mpstat command'''		'''Examining the Output of the mpstat command'''

	%user= % of time the processor spent executing user programs and daemons		%user= % of time the processor spent executing user programs and daemons
	%nice= % of time the processor spent executing programs and daemons that had nondefault nice values		%nice= % of time the processor spent executing programs and daemons that had nondefault nice values
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	'''iostat (input/output statistics)'''		'''iostat (input/output statistics)'''

	Measusres the flow of information to and from disk devices.		Measusres the flow of information to and from disk devices.
	Displays CPU statistics similar to mpstat		Displays CPU statistics similar to mpstat
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	'''sar (system activity reporter)'''		'''sar (system activity reporter)'''

	Displays more information than the mpstat or iostat command		Displays more information than the mpstat or iostat command
	Displays CPU statistics by default		Displays CPU statistics by default
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	'''Common options with the sar caommand'''		'''Common options with the sar caommand'''

	CPU Usage of ALL CPUs (sar -u) Default		CPU Usage of ALL CPUs (sar -u) Default
	CPU Usage of Individual CPU or Core (sar -P)		CPU Usage of Individual CPU or Core (sar -P)
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	'''Other Performance Monitoring Utilities'''		'''Other Performance Monitoring Utilities'''

	top utility (discussed in Chapter 9)		top utility (discussed in Chapter 9)
	free command can be used to display the total amounts of physical and swap memory (in Kilobytes) and their utilizations.		free command can be used to display the total amounts of physical and swap memory (in Kilobytes) and their utilizations.
	vmstat command indicates more information than the free command to indicate whether more physical memory is required.		vmstat command indicates more information than the free command to indicate whether more physical memory is required.