Installing and Configuring Linux LVM with Multipath simple Steps

Configuring Multipath Linux LVM Steps.

#To Install Multipath supportable RPM's
yum install -y device-mapper-multipath*

#Generate Sample Multipath Configuration
mpathconf --enable --user_friendly_names y

#Start Multipathd Services
systemctl start multipathd.service

#To Check Netapp SAN LUN Disks and Paths
sanlun lun show -p

# Configure Multipath Alias
vim /etc/multipath.conf

#check the Status of Configured Alias reflected 
multipath -v2

# List Created Disk Paths
ls -al /dev/mapper/

#Create Linux LVm Partition
fdisk /dev/mapper/DATA-DISK

#Add Mapping to Partition
kpartx -a /dev/mapper/DATA-DISK

#Create Physical Volume
pvcreate /dev/mapper/DATA-DISKp1

#Create Volume Group
vgcreate ATE-PROD /dev/mpath/DATA-DISKp1 /dev/mpath/DATA-DISKp1

#Create LV with 100% Free Space
lvcreate -n U03 -l 100%FREE DATAVG

#File System Creation in Newly Created LVM
mkfs -t ext3 /dev/DATAVG/U03

#Mount Permanently using fstab Entry
vi /etc/fstab

/dev/DATAVG/U03  /u03    ext3    defaults        1 2

Java Update Guide Centos 7 / RHEL 7

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# java -version
java version "1.7.0_141"
OpenJDK Runtime Environment (rhel-2.6.10.1.el7_3-x86_64 u141-b02)
OpenJDK 64-Bit Server VM (build 24.141-b02, mixed mode)

32 Bit Java Download Link
# wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u144-b01/090f390dda5b47b9b721c7dfaa008135/jdk-8u144-linux-i586.tar.gz"

64 Java Download Linux
# wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/8u144-b01/090f390dda5b47b9b721c7dfaa008135/jdk-8u144-linux-x64.tar.gz"

# du -sh jdk-8u144-linux-x64.tar.gz
177M    jdk-8u144-linux-x64.tar.gz
# tar -xvf jdk-8u144-linux-x64.tar.gz


[root@Arkit-Serv java]# update-alternatives --install /usr/bin/java java /opt/java/jdk1.8.0_144/bin/java 100
[root@Arkit-Serv java]# update-alternatives --config java

There are 3 programs which provide 'java'.

  Selection    Command
-----------------------------------------------
*+ 1           java-1.7.0-openjdk.x86_64 (/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.141-2.6.10.1.el7_3.x86_64/jre/bin/java)
   2           /usr/java/jdk1.8.0_144/jre/bin/java
   3           /opt/java/jdk1.8.0_144/bin/java

Enter to keep the current selection[+], or type selection number: 3


[root@Arkit-Serv java]# export JAVA_HOME=/opt/java/jdk1.8.0_144/
[root@Arkit-Serv java]# export JRE_HOME=/opt/java/jdk1.8.0_144/jre
[root@Arkit-Serv java]# export PATH=$PATH:/opt/java/jdk1.8.0_144/bin:/opt/java/jdk1.8.0_144/jre/bin

# java -version
java version "1.8.0_144"
Java(TM) SE Runtime Environment (build 1.8.0_144-b01)
Java HotSpot(TM) 64-Bit Server VM (build 25.144-b01, mixed mode)

That's it Java Updated.

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Failed To Load SELINUX policy. Freezing error after reboot on Centos 7/RHEL7?

system[1]: Failed to load SELinux policy. Freezing error after reboot on Centos 7/RHEL7?

 Most of the time you will get this error "while resetting the root password". That means you are not correctly reset the root password (or) mismatch words in the "touch /.autorelabel" command.

"touch /.autorelabel" -->  create an hidden file under the slash which means SELinux will automatically relabel the SELinux policy when server is booting

SELinux Load Error

1) Reboot your machine

2) Loading boot menu then press key to stop the boot menu, edit(press 'e') kernel line.

Change String SELInux

3) Goto "linux16" word and append the word "selinux=0".

4) reboot the server.

That't it.

Installing nagios core got error - Resolution

While installing nagios core got error make all command on RHEL7/centos 7:

while installing nagios core on RHEL7  got the issue that is "(cd angularjs && unzip -u angular-1.3.9.zip),/bin/sh: unzip: command not found". The error occur after enter the command make all . On my server have already installed gcc so the error was coming from some other dependency requirement.

[root@serverx nagios-4.1.1]# make all
gcc -Wall -I.. -g -O2 -DHAVE_CONFIG_H -DNSCORE -o nagiostats nagiostats.c  -lm  ../lib/libnagios.a
make[1]: Leaving directory `/tmp/nagios-4.1.1/base'
cd ./cgi && make
make[1]: Entering directory `/tmp/nagios-4.1.1/cgi'
make[1]: Nothing to be done for `all'.
make[1]: Leaving directory `/tmp/nagios-4.1.1/cgi'
cd ./html && make
make[1]: Entering directory `/tmp/nagios-4.1.1/html'
(cd angularjs && unzip -u angular-1.3.9.zip)
/bin/sh: unzip: command not found
make[1]: * [all] Error 127
make[1]: Leaving directory `/tmp/nagios-4.1.1/html'
make: * [all] Error 2
[root@serverx nagios-4.1.1]#


Observed the above error i.e "unzip command not fund", Installed the unzip package by following below command

# yum install -y unzip

After installed the unzip package, rerun the configure command issue has been resolved.


That's it.

RHEL7 installation Kickstart File

I have made Kickstart (Auto Answer File) Using Kcikstart configuration generator tool with LVM partitioning included

[root@ArkIT ~]#cat ks.cfg
#platform=x86, AMD64, or Intel EM64T
#version=DEVEL
# Install OS instead of upgrade
install
# Keyboard layouts
keyboard 'us'# Reboot after installation
reboot
# Root password
rootpw --iscrypted $1$tS7oWXXF$X.HS5njtcfPpxHgW9pFtX.
# System timezone
timezone Africa/Abidjan
# Use network installation
url --url="http://192.168.4.27/rhel7"
# System language
lang en_US
# Firewall configuration
firewall --disabled
# Network information
network  --bootproto=dhcp --device=eth0
# System authorization information
auth  --useshadow  --passalgo=sha512
# Use graphical install
graphical
# Run the Setup Agent on first boot
firstboot --enable
# SELinux configuration
selinux --disabled

# System bootloader configuration
bootloader --location=mbr
# Clear the Master Boot Record
zerombr
# Partition clearing information
clearpart --all --initlabel
volgroup rhel --pesize=4096 PV0
part PV0 --fstype=lvmpv --ondisk=sda --size=50000
part /boot --fstype=xfs --size=500
logvol / --vgname=rhel --name=root --fstype=xfs --size=10000
logvol /var --vgname=rhel --name=var --fstype=xfs --size=8000
logvol swap --vgname=rhel --name=swap --fstype=swap --size=8000
logvol /home --vgname=rhel --name=home --fstype=xfs --size=7000
logvol /usr --vgname=rhel --name=usr --fstype=xfs --size=7000

%packages
@base
@core
@desktop-debugging
@dial-up
@fonts
@gnome-desktop
@guest-agents
@guest-desktop-agents
@input-methods
@internet-browser
@mariadb
@multimedia
@print-client
@x11
kexec-tools

%end

%post
useradd ravi
echo password | passwd ravi
%end

A Major Difference Between RHEL 6 vs RHEL 7 Here you go

RHEL 7 vs RHEL 6

Red Hat Enterprise Linux 7 is an Light weight and minimized Operating system. RHEL 7 changes are huge effect to enterprise.

Let's see what changed in RHEL 7 as per administration prospective.

• First one is Anaconda Installer Completely new.
• Grub version updated from 0.97 to Grub 2 fast booting
• Procedure of bypassing root password at booting process completely different than RHEL 6/5 
• There is no SysV Initd in RHEL 7 it's an new Systemd
• Run Levels are changed to Targets.
• Default file system in RHEL 7 is XFS. XFS file system supports 550TB of each partition size in 64-bit.
• Directories /bin /sbin /lib and /lib64 are moved under /usr/
• Network Interface Names are changed from eth0 to ens.xxx
• New concept to create multiple profiles top of one Ethernet card, No need of changing IP addresses and settings every time when you connect different networks, simply activate different profile.
• GNOME version changed from 2 to 3
• No classic registration system, completely changed to Red Hat subscription Manager
• Default database is MariaDB instead of MySQL
• Cluster Manager has been changed to Pacemaker and Corosync
• Ifconfig command is deprecated, replaced with ip command
•  User Identification Numbers (UID's) changed from 500 to 1000, which means when you create new normal user in RHEL 7 will get UID from 1000 to 65534
• locate command is changed to mlocate
•  yum commands are changed little bit

 

Feature Name	RHEL 6	RHEL 7
Default File System	Ext4	XFS
Kernel Version	2.6.xx	3.10.xx
Release Name	Santiago	Maipo
Gnome Version	GNOME 2	GNOME 3.8
KDE Version	4.6	4.1
Release Date	10-Nov-10	10-Jun-14
NFS Version	NFS 4	NFS 4.1. NFS V2 is deprecated in RHEL 7
Samba Version	3.6	4.4
Default Database	MariaDB	MySQL
Cluster Resource Manager	Rgmanager	Pacemaker
Network Grouping	Team Driver will support multiple types of Teaming methods called Active-Backup, Load-balancing and Broadcase	Bonding can be done as Active-Backup, XOR, IEEE and Loac Balancing
KDUMP	RHEL 7 can be supported up to 3TB	Kdump does't support with large RAM Size
Boot Loader	Grub 2 /boot/grub2/grub.cfg	Grub 0.97  /boot/grub/grub.conf
File System Check	xfs_replair - Inode blockmap checks -Inode allocation map checks -Inode size check -Directory check -Path Name check -Link count check -Freemap check -Super block check	e2fsck -Inode check. Block and size check --Directory Structure check -Directory Link Check -reference count check -Group Summary Check
Process ID	Systemd (1)	Initd (1)
Port Security	Firewalld instead of iptables. Iptables can also support with RHEL 7, but we can't use both of them at the same time. Firewall will not allow any port until and unless you enabled it.	iptables by default service port is enabled when service is switched on.
Boot Time	40 Sec	20 Sec
File System Size	EXT4 16TB with XFS 100TB	XFS 500TB with EXT4 16TB
Processor Architecture	32Bit and 64Bit	Only 64Bit.
Network Configuration Tool	steup	nmtui
Hostname Config File	/etc/sysconfig/network	/etc/hostname No need to edit hostname file to write permanent hostname simply use hostnamectl command
Interface Name	eth0	ens33xxx
Managing Services	service sshd start service sshd restart chkconfig sshd on	systemctl start sshd.service systemctl restart sshd.service systemctl enable sshd.service
System Logs	/var/log/	/var/log journalctl
Run Levels	runlevel 0 - Power Off runlevel 1 - Single User Mode runlevel 2 - Multi User without Networking runlevel 3 - Multi User CLI runlevel 4 - Not USed runlevel 5 - GUI Mode runlevel 6 - Restart	There is no run levels in RHEL 6. Run levels are called as targets Poweroff.target rescue.target multi-user.target graphical.target reboot.target
UID Information	Normal User UID will start from 500 to 65534 System Users UID will start from 1 to 499	Normal User UID start from 1000 - 65534 System Users UID will start from 1 to 999 Because Services are increased compare to RHEL 6
By Pass Root Password Prompt	append 1 or s or init=/bin/bash to Kernel command line	Append rd.break or init=/bin/bash to kernel command line
Rebooting and Poweroff	poweroff - init 0 reboot - init 6	systemctl poweroff systemctl reboot
YUM Commands	yum groupinstall yum groupinfo	yum group install yum group info

Thanks, please provide your valuable feedback on the same.