Transcript Linux+ Guide to Linux Certification

Linux+ Guide to Linux
Certification, Third Edition
Chapter 6
Advanced Installation
Objectives
• Describe the types and structure of SCSI devices
• Explain the different levels of RAID and types of
RAID configurations
• Describe how to install Linux from source files on
CDs, USB flash memory drives, hard disks, or
network servers
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Objectives (continued)
• Install Fedora Linux using a kickstart file
• Troubleshoot the installation process
• Access an installed system using System Rescue
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Advanced Storage Configuration:
SCSI Hard Disk Configuration
• SCSI (Small Computer System Interface): a way to
connect multiple peripherals to the system
• Three types of SCSI disk configurations:
– Parallel SCSI
– Serial Attached SCSI
– iSCSI
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Parallel SCSI Configuration
• Ribbon cables transmit information between hard
disk and SCSI controller
• Terminator: prevents signals from bouncing back
and forth on a connection cable
• SCSI ID: uniquely identifies devices attached to a
SCSI controller
– Target ID
– Identifies priority
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Parallel SCSI Configuration
(continued)
Figure 6-1: Connecting parallel SCSI devices
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Parallel SCSI Configuration
(continued)
Table 6-1: Common SCSI standards
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Parallel SCSI Configuration
(continued)
• Configuration steps:
– Verify all SCSI components support the same
technology
– Ensure that components are connected properly
– Make sure system recognizes hard drives at startup
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Serial Attached SCSI Configuration
• Serial attached hard disks connected to SCSI
controller via serial cables with small serial
connectors
– More than 60,000 devices per controller
• Configuration steps:
– Connect hard disk to controller via correct serial
cable
– Ensure that hard disk is detected by system or SCSI
BIOS
– The rest is performed automatically by controller
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iSCSI Configuration
• Internet SCSI (iSCSI): uses network cables to
transfer data to/from remote hard disks
– iSCSI initiator: computer connected to remote hard
disk
• Can be software or hardware
– iSCSI target: remote hard disk
• Contained within remote network attached device
• Configuration settings vary by manufacturer
– Must specify configuration settings during the Linux
installation
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RAID Configuration
• Fault tolerant: device exhibiting minimum downtime
after failure
• Redundant Array of Inexpensive Disks (RAID):
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Typical implementation of fault tolerant disk
Can be used to speed up access to hard disk
Combines several HDDs’ storage space
Seven RAID configurations
Hardware-, software-, or firmware-based
• Different configuration process for each type
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RAID Configuration (continued)
• Spanning: two HDDs seen as one volume
– RAID level 0, not fault tolerant
– Good when need large amount of space in single
volume
• Disk striping: write a portion of the information to
each of multiple HDDs
– RAID level 0: not fault tolerant
– Decreases read/write time
• Disk mirroring: two identical hard disks
– RAID level 1: fault tolerant
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RAID Configuration (continued)
• RAID level 2: no longer used
• Disk striping with parity: write portions information
to different HDDs and maintain parity information
– RAID level 5: fault tolerant
• Most common RAID configuration
• Improves on RAID levels 3 and 4
– Parity bits indicate what data is where
• Intermixed on the HDDs that contain the data
• Can be used to re-generate data when HDD fails
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RAID Configuration (continued)
• Disk striping with parity (continued):
– Requires three HDDs minimum
– If any of the HDDs fail, the information can be
recovered from the other HDDs
– RAID level 6: uses two sets of parity bits for added
fault tolerance
• Allows two HDDs to fail simultaneously while
remaining fault tolerant
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RAID Configuration (continued)
Figure 6-6: Organization of data on RAID level 5
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Installation Methods
• International Standards Organization (ISO) image:
large file containing exact copy of contents of a
CD-ROM or DVD
• DVD is the most common and easiest method for
installing Linux
• Other methods for installing Linux
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Multiple CDs
USB flash memory drive
ISO image on local hard disk
ISO image through network server
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CD Installation
• Requires six CDs
• First CD contains the installation program
– Boot the computer using the first CD, then make
appropriate choices within the installation program
– Will be prompted to insert remaining CDs when
necessary
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USB Flash Drive Installation
• BIOS can boot the computer from a flash memory
drive
• Need to download Linux onto the flash memory
drive
– Overwrites the existing filesystem on the drive
– From Windows, can use free utilities
• e.g., LiveUSB Creator
– From another Linux computer, use dd command
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Hard Disk Installation
• May install Linux directly from ISO images on hard
disk
– Must have sufficient free space outside partition
containing ISO images
• Use DVD, installation CD-ROM or bootable USB
flash memory drive to start installation
• Use options in the welcome screen to perform non
standard installation
• Installation will be text-based
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Hard Disk Installation (continued)
Figure 6-3: Selecting a nonstandard installation method
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Hard Disk Installation (continued)
Figure 6-4: Selecting the installation media location
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Hard Disk Installation (continued)
Figure 6-5: Specifying the location of the Fedora ISO image on
the hard disk
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Network-Based Installations
• Requires installation startup DVD, CD-ROM or
bootable USB flash memory drive
– Contains NIC drivers and programs allowing
connection to server
– Select language, keyboard setting, and protocol
• Installation via one of following protocols:
– Network File System (NFS)
– File Transfer Protocol (FTP)
– Hypertext Transfer Protocol (HTTP)
• Must configure network settings
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Network-Based Installations
(continued)
Figure 6-6: Specifying the location of the
Fedora ISO image on an NFS server
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Network-Based Installations
(continued)
Figure 6-6: Specifying the location of the
Fedora ISO image on an HTTP server
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Automating Linux Installations
• Deploy several Linux servers and workstations
requiring same configuration
• Kickstart file: automated installation script
– Specifies normal OS installation choices
– ks.cfg
– Contains sections on system configuration, disk
partitioning, and package selection
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Automating Linux Installations
(continued)
• Kickstart configuration: configure a new kickstart
file
– Use Kickstart Configurator tool
• To use ks.cfg:
– Place ks.cfg on CD, DVD, floppy disk, or hard disk
partition
– Boot from installation startup DVD
– At welcome screen, modify the boot option, and
specify ks.cfg file and its location
• Installation will run without prompting user
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Automating Linux Installations
(continued)
Figure 6-8: The Kickstart Configurator
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Troubleshooting Installation
• Computers typically have different BIOS
configurations
– Installing on different computers is rarely the same
• Problems primarily related to hardware support or
configuration
– Typically fixed by changing hardware configuration
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Problems Starting the Installation
• Check BIOS boot order
• Check that battery supporting BIOS is providing
power
• Choose device to boot from at system startup by
pressing a special key
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Problems During Installation
• For graphical installation, video card and mouse
must be detected
– Appropriate drivers must be loaded
– Video card may not be supported by mode and
resolution of graphical installation
• Install system with basic video driver
– Mouse does not work
• Use text-based installation
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Problems During Installation
(continued)
Figure 6-9: Starting a text mode Fedora installation
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Problems During Installation
(continued)
Figure 6-10: The Fedora welcome screen during a text
mode installation
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Problems During Installation
(continued)
• Installation freezes
– Disable Plug-and-Play support in BIOS prior to
installation
• Installation ends abnormally
– “fatal signal 11” error displayed
• Could be problem with RAM
• Often fixed by turning off CPU cache memory or
increasing number of wait states in the BIOS
• Could also be RAM or CPU voltage issue
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Problems During Installation
(continued)
• Other failure causes include an AMD K6 processor,
laptop power management conflicts, overclocked
CPUs
• Overclocked: running a processor at a higher
speed than it is rated for
– May lead to increased performance
– Produces more heat on processor
• May result in computer crashes
• Installation may fail to place boot loader properly
– Ensure that / partition starts before 1024th cylinder
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Problems After Installation
• May have problems if installation program did not
detect computer hardware properly or certain
programs were not installed
• Installation log file: records actions that occur or fail
during installation
– /root/install.log: Lists packages installed or not
installed
– /root/install.log.syslog: Lists all system events that
occurred during installation
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Problems After Installation (continued)
• To verify hardware settings, examine contents of
/proc directory or boot-up log files
– For CPU information, view /proc/cpuinfo
– For RAM information, view /proc/meminfo
– For list of modules, view /proc/modules
• To view hardware detected at boot time, use
dmesg command
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Problems After Installation (continued)
Table 6-2: Files commonly found in the /proc directory
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Problems After Installation (continued)
Table 6-2 (continued): Files commonly found in the /proc directory
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System Rescue
• System Rescue: A small bootable Linux kernel and
virtual filesystem used to fix problems
– Used to fix:
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The boot loader
Filesystems and partitions
The configuration file
Drivers
• Can select Rescue installed system at Fedora
installation welcome screen
– Many options regarding how to rescue
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System Rescue (continued)
Figure 6-11: Selecting System Rescue mount options
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System Rescue (continued)
Figure 6-12: Selecting System Rescue options
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System Rescue (continued)
Figure 6-13: Using the System Rescue BASH shell
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Summary
• Parallel SCSI HDDs are uniquely identified by a
SCSI ID and attach to a controller via a terminated
cable
• SAS SCSI HDDs transfer information to hard disks
using a serial cable
• iSCSI is a SAN technology used to transfer
information from iSCSI initiators to iSCSI targets
across a network
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Summary (continued)
• RAID is used in Linux servers to combine several
hard disks into one for speed or fault tolerance
• RAID can be implemented by software, hardware,
or the system BIOS
• Different levels of RAID determine how disks are
combined and written to
• Linux can be installed using files located on CD,
USB flash drive, hard disk, and NFS, FTP, and
HTTP servers
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Summary (continued)
• Use a kickstart file to simplify the installation of
Linux on several computers
• Unsupported video cards, overclocked CPUs, PnP
support, and improper RAM settings can cause an
installation to fail
• The /proc directory contains information regarding
detected hardware and is useful when verifying
whether an installation was successful
• You can use the System Rescue feature to access
and repair a damaged Linux installation
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