Download Things to Know while installing Linux OS

Things to Know while installing
Linux OS
Physical/Standalone
• Physical server installation:
1. Automated installation: kickstart
2. Manual installation:
vs Vitrulization
Physical Server
Physical Server
Automated installation
•
Kickstart: Kickstart is the process to automatically perform unattended operating
system installation and configuration.
Manual installation
1.
2.
access to hardware and install from dvd
Out of band management tool:
* ILO: hp's integrated lights out management tool
* IDRAC: Dell's Integrated Dell Remote Access Controller
* IMM: IBM management module
* CIMC: Cisco Integrated Management Controller
* ILOM: Oracle Integrated Lights Out Manager for solaris
* KVM-over-IP switch: Raritan
Virtulization
• Virtualization is the creation of a virtual (rather than actual) version of
something, such as an operating system, a server, a storage device or
network resources.
• Virtual machines are nothing but software computer, which acts and
performs like physical computers.
Virtulization
Virtulization
To achieve virtulization we use a software called Hypervisor.
• Hypervisor: A hypervisor or virtual machine monitor (VMM) is a piece of
computer software, firmware or hardware that creates and runs virtual
machines. A computer on which a hypervisor is running one or more
virtual machines is defined as a host machine. Each virtual machine is
called a guest machine.
• There are Two types of Hypervisor:
*Type1 Hypervisor
*Type2 Hypervisor
Video Link`
Definition Link
Hypervisor
Difference betwn Type1 and Type2
Hypervisor
Type1
Hypervisor
This type of hypervisor is
deployed as a bare-metal
installation. This means that
the first thing to be installed
on a server as the operating
system will be the hypervisor.
The benefit of this software is
that the hypervisor will
communicate directly with
the underlying physical server
hardware. Those resources
are then paravirtualized and
delivered to the running
VMs. This is the preferred
method for many production
systems.
Type1 Hypervisor
• List of Type1 Hypervisors:
*VMware vSphere / ESXi
*Microsoft Windows Server 2012 Hyper-V (or the free Hyper-V
Server 2012)
*Xen / Citrix XenServer
*Red Hat Enterprise Virtualization (RHEV)
* KVM
Type2
Hypervisor
This model (shown below) is
also known as a hosted
hypervisor. The software is not
installed onto the bare-metal,
but instead is loaded on top of
an already live operating system.
For example, a server running
Windows Server 2008R2 can
have VMware Workstation 8
installed on top of that OS.
Although there is an extra hop
for the resources to take when
they pass through to the VM –
the latency is minimal and with
today’s modern software
enhancements, the hypervisor
can still perform optimally.
Type2 Hypervisor
• List of Type2 Hypervisor:
• VMware Workstation,
• VirtualBox,
• VMware Fusion,
• MED-V,
• Windows Virtual PC,
• Parallels,
• MokaFive
Installation in virtual machine
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•
•
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Manual
Clone
Template
Link for Video
BootStages
•BIOS
•MBR
•GRUB
•KERNEL
•INIT
•RUNLEVEL
Linux boot stages
Link for boot stages
boot stages
• SAN : A Storage Area Network
•
Storage
is an enterprise-level storage network of several (often,
hundreds) of hard drives managed by an intelligent device. This allows for maximally
efficient use of all available storage space, lowering total costs of ownership (TCO) and increasing
return on investment (ROI). Most importantly, if a drive crashes, the your data is not lost!.
Servers that host applications communicate with a SAN through fiber channel network
equipment (iSCSI and F/C over IP are also supported), and the SAN determines where data is
stored. If a hard drive fails for some reason, the other hard drives in the storage network
essentially rebuild the data through a series of algorithms so no information is lost.
DAS: Direct-attached storage is digital storage directly attached to the computer accessing it, as
opposed to storage accessed over a computer network. Examples of DAS include hard drives,
optical disc drives, and storage on external drives.
Raid
• RAID is an acronym for Redundant Array of Independent (or Inexpensive)
Disks. In fact, RAID is the way of combining several independent and
relatively small disks into a single storage of a large size. The disks included
into the array are called array members. The disks can be combined into
the array in different ways which are known as RAID levels. Each of RAID
levels has its own characteristics of:
• Fault-tolerance which is the ability to survive of one or several disk
failures.
• Performance which shows the change in the read and write speed of the
entire array as compared to a single disk.
• The capacity of the array which is determined by the amount of user data
that can be written to the array. The array capacity depends on the RAID
level and does not always match the sum of the sizes of the RAID member
disks. To calculate the capacity of the particular RAID type and a set of the
member disks you can use a free online RAID calculator.
• http://mazzakolinux.com/raid-redundant-array-of-independent-disks/
RAID storage techniques
• Striping - splitting the flow of data into blocks of a certain size
(called "block size") then writing of these blocks across the RAID one by
one. This way of data storage affects on the performance.
• Mirroring is a storage technique in which the identical copies
of data are stored on the RAID members simultaneously. This type
of data placement affects the fault tolerance as well as the
performance.
• Parity is a storage technique which is utilized striping and
checksum methods. In parity technique, a certain parity
function is calculated for the data blocks. If a drive fails, the
missing block are recalculated from the checksum, providing
the RAID fault tolerance.
Directory Vs Filesystem
• Directory - a place where files and sub directories are stored
• File System - is a directory which occupies separate space in the hard drive. In
abstract sense, a filesystem is "something that has a capacity to hold files and
directories". A filesystem might be contained in a disk partition (e.g.
/dev/sda1), in a LVM logical volume (/dev/vg00/lvol1) or in a CDROM/DVD
(/dev/scd0).
Filesystem Type
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Ext2
Ext3
ext4
Ntfs
Fat32
xfs
Linux File Systems: Ext2 vs Ext3 vs Ext4
Limitations of file system
http://www.howtogeek.com/howto/33552/htg-explainswhich-linux-file-system-should-you-choose/
Disk Partition
• An operating system like Windows / Linux can be installed on a single,
unpartitioned hard disk. However, the ability to divide a hard disk into multiple
partitions offers some important advantages. If you are running Linux on
server consider following facts:
• Ease of use - Make it easier to recover a corrupted file system or operating
system installation.
• Performance - Smaller file systems are more efficient. You can tune file system
as per application such as log or cache files. Dedicated swap partition can also
improve the performance (this may not be true with latest Linux kernel 2.6).
• Security - Separation of the operating system files from user files may result
into a better and secure system. Restrict the growth of certain file systems is
possible using various techniques.
• Backup and Recovery - Easier backup and recovery.
• Stability and efficiency - You can increase disk space efficiency by formatting
disk with various block sizes. It depends upon usage. For example, if the data is
lots of small files, it is better to use small block size.
• Testing - Boot multiple operating systems such as Linux, Windows and FreeBSD
from a single hard disk.
Partition types
• Primary partitions is a partition that is needed to store and boot an
operating system, In general, you would install the operating system in a
primary partition. Maximum of four primary partition can exist. If we need
more than four partition we can make Three primary partition and Make one
Extended partition and many logical partition under Extended partition.
Extended partition can be sub-divided into logical drives and is
viewed as a container for logical drives, where data proper is located.
An extended partition is not formatted. The extended partition is used
only for creating a desired number of logical partitions.
Logical partitions are the partitions that are created in the extended
partition area. A logical partition is a way to extend the initial limitation of four
partitions. An extended partition can contain up to 24 logical partitions.
Partition
Swap partition
• Swap space in Linux is storage allocated from hard drive to act as
•
•
if
If
virtual ram. Swap space in Linux is used when the amount of physical
memory (RAM) is full. If the system needs more memory resources and
the RAM is full, inactive pages in memory are moved to the swap space.
While swap space can help machines with a small amount of RAM, it
should not be considered a replacement for more RAM. Swap space is
located on hard drives, which have a slower access time than physical
memory.
Swap space can be a dedicated swap partition (recommended), a swap
file, or a combination of swap partitions and swap files.
How to allocate swap: if n is amount of physical ram then,
n <= 2 then swap = 2 x n for eg: if ram 2G then swap = 2x2=4G
n > 2 then swap = 1 + n for eg: if ram 3G then swap = 1+3=4G
LVM
• In Linux, Logical Volume Manager (LVM) is a device mapper target that provides
logical volume management for the Linux kernel. Most modern Linux
distributions are LVM-aware to the point of being able to have their root file
systems on a logical volume.
• Physical Volume
• Volume Group
• Logical Volume
• In order to create a logical volume we need to follow a certain procedure.
• Logical volume can only be created under Volume Group, and Volume group can
only be created under Physical Volume. Physical volume can be created from
partitions.
• One partition equals to one physical volume.
• Whole physical volume has to be give to one volume group
• One volume group can be created from multiple physical volume
• One volume group can contain multiple logical volume
LVM
LVM
File sizes