Installation setup of ansible in linux step by step guide

August 31, 2018 Add Comment Edit

Installation Setup Of Ansible on Linux | In this article we learn about the installation setup of ansible

Two types of machines are required to create ansible deployment setup

Control machine: Ansible needs to install on one machine.This machine is called control machine.

Remote machine: need to define the systems in the inventory file (which is the text file) on which configuration will done.Overall we can say which machine is controlled by control machine is called remote machine.

Many remote machines are handled by one controlling machine. For that purpose we need to install ansible on the controlling machine.

Installation Requirement to setup ansible

Python2 and Python3 must be installed to run the ansible.

NOTE:Windows isn’t supported for the control machine

Ansible does not required database and does not required any daemon to run the ansible service .Ansible connect to the remote nodes through ssh by default.

How to install ansible on centos 7/rhel 7/Ubuntu 16.04

To install the ansible package on rhel machine you need to enable epel repo.

After install and enabling epel repository, we can install Ansible using below command.

yum install ansible -y

installation setup of ansible

After running the above command you can manage remote machine through ansible.

In Ubuntu there is no need to install extra repository. By default ansible package is available in Ubuntu. We can install ansible in Ubuntu using the below command.

apt-get install ansible -y

After installing ansible we can verify the version of ansible by hitting the below command.

ansible --version

ansible version

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Brief Introduction of Ansible

August 31, 2018 Add Comment Edit

Brief Introduction of Ansible

Ansible is an IT automation open source tool which automates application deployment,managing and configuring on many numbers of systems very easily and doing infra service orchestration ,cloud provisioning and many other things.

What is Ansible

Ansible is very easy to deploy because it does not use any agents on the client side.

Ansible uses playbook to execute automation jobs and Play book uses YAML language which is very simple language and easy to understand for the human.

Ansible is totally agentless which means Ansible works by associating your hubs through ssh(by default).

In the wake of associating with your hubs, Ansible pushes little projects called as "Ansible Modules". Ansible runs that modules on your hubs and evacuates them when wrapped up. Ansible manages your inventory in simple text files (These are the hosts file). Ansible uses the hosts record where one can aggregate the hosts and can control the activities on a particular gathering in the playbooks.

Ansible

Advantage of Ansible

Agentless: Ansible is completely agentless which means Ansible works by connecting your nodes through ssh.
Documentation: Documentation of ansible is very simple and easy
Ansible uses YAML language which is very simple language and easy to understand.
Ansible is open source IT automation tools.

yum:
     name: httpd
     state: latest

The above task connect to the node and check if httpd package is already installed and it is latest version or not.If it it latest version nothing will be happen.

How ansible works

Ansible need to be installed on one machine its called control machine and need to define the systems in the inventory file which is the text file on which configuration will done.

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Snapshot of Logical Volume and Restore in LVM on Rhel 7/Centos 7/Oracle 7 Linux

August 30, 2018 Add Comment Edit

LVM Snapshots of Logical Volume on Rhel 7/Centos 7/Oracle 7 Linux are space productive pointing time duplicates of lvm volumes.

It works just with lvm and expend the space just when changes are made to the source intelligent volume to depiction volume.

If source volume has a huge changes made to sum of 500MB the same changes will be made to the snapshot volume.

Incase the preview comes up short on capacity, we can utilize lvextend to develop.

On the off chance that we have incidentally erased any record in the wake of making a Snapshot we don't need to stress in light of the fact that the preview have the first document which we have erased.

To remove the snapshot we can use lvremove command.

Step 1: Create LVM Snapshot

First, check for free space in volume group to create a new snapshot.For that we are using using following vgs command.

# vgs

VG #PV #LV #SN Attr VSize VFree

VolGroup 1 2 0 wz--n- 7.51g 0

testvg 2 1 0 wz--n- 3.99g 1.99g

# lvs

LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert

lv_root VolGroup -wi-ao---- 6.71g

lv_swap VolGroup -wi-ao---- 816.00m

testlv testvg -wi-ao---- 2.00g

You see, there is 1.99GB of free space left in above vgs output. So, let’s create a snapshot for one of my volume named testlv.

For an example we are going to create only 1GB snapshot volume using following commands.

# lvcreate -L 1GB -s -n testlv_snap /dev/testvg/testlv

Logical volume "testlv_snap" created

Where

1GB= Size of snapshot Iam creating here.

-s= Creates snapshot.

-n= Creates name for the snapshot.

testlv_snap= New snapshots name.

/dev/testvg/testlv= Volume which we are going to create a snapshot.

create snapshot

We can use the below command to list new created snapshot.

# lvs

LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert

lv_root VolGroup -wi-ao---- 6.71g

lv_swap VolGroup -wi-ao---- 816.00m

testlv testvg owi-aos--- 2.00g

testlv_snap testvg swi-a-s--- 1.00g testlv 0.00

Snapshot of Logical Volume and Restore in LVM

List snapshot

You see above, a snapshot was created successfully.

# df -Th /dev/mapper/testvg-testlv

Filesystem Type Size Used Avail Use% Mounted on

/dev/mapper/testvg-testlv ext4 2.0G 67M 1.9G 4% /testlvm

Let’s add some new files into testlv.

Now check the volume using the follwing command.

#lvs

LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert

lv_root VolGroup -wi-ao---- 6.71g

lv_swap VolGroup -wi-ao---- 816.00m

testlv testvg owi-aos--- 2.00g

testlv_snap testvg swi-a-s--- 1.00g testlv 0.13

You see, 0.13% of snapshot volume was used now.

If we copy more than 1GB of files in testlV you will get error message appear On the screen Input/output error, it means out of space in snapshot.

Step 2: Extend Snapshot in LVM

First we check available PE using vgdisplay command

# vgdisplay

--- Volume group ---

VG Name testvg

System ID

Format lvm2

Metadata Areas 2

Metadata Sequence No 4

VG Access read/write

VG Status resizable

MAX LV 0

Cur LV 2

Open LV 1

Max PV 0

Cur PV 2

Act PV 2

VG Size 3.99 GiB

PE Size 4.00 MiB

Total PE 1022

Alloc PE / Size 768 / 3.00 GiB

Free PE / Size 254 / 1016.00 MiB

VG UUID mz7AN3-jsR0-rnsQ-XpvM-2W0N-M8q8-pki2kB

# lvextend -l +254 /dev/testvg/testlv_snap

Extending logical volume testlv_snap to 1.99 GiB

Logical volume testlv_snap successfully resized

Now verify the size using the below command.

# lvdisplay /dev/testvg/testlv_snap

--- Logical volume ---

LV Path /dev/testvg/testlv_snap

LV Name testlv_snap

VG Name testvg

LV UUID eVvo1m-OZhv-PfP2-caja-r67k-W2o6-PD9Fcm

LV Write Access read/write

LV Creation host, time localhost.localdomain, 2018-06-16 08:17:05 +0530

LV snapshot status active destination for testlv

LV Status available

# open 0

LV Size 2.00 GiB

Current LE 512

COW-table size 1.99 GiB

COW-table LE 510

Allocated to snapshot 0.07%

Snapshot chunk size 4.00 KiB

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 256

Block device 253:3

# lvs

LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert

lv_root VolGroup -wi-ao---- 6.71g

lv_swap VolGroup -wi-ao---- 816.00m

testlv testvg owi-aos--- 2.00g

testlv_snap testvg swi-a-s--- 1.99g testlv 0.07

Step 3: Restoring Snapshot or Merging

To restore the snapshot, we need to un-mount the file system first.

# unmount /testlvm

Just check for the mount point whether its unmounted or not.

# df -h

Here our mount has been unmounted, so we can continue to restore the snapshot. To restore the snap using command lvconvert.

# lvconvert --merge /dev/testvg/testlv_snap

Merging of volume testlv_snap started.

testlv: Merged: 100.0%

Merge of snapshot into logical volume testlv has finished.

Logical volume "testlv_snap" successfully removed

After the merge is finished, snapshot volume will be expelled naturally. Now we can check partition space using the below command.

# df -Th

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How to Extend Logical Volume in rhel 7/Centos 7/Oracle 7 Linux LVM

August 30, 2018 Add Comment Edit

Extend Logical Volume In rhel 7/CentOS 7/ Oracle 7 |In creating Logical Volume section we create testlv with 5GB

We want to increase the size of the LV from 5GB to 10GB

we can do it two different ways

1. Extend LV Size with new hardDisk

2. Extend LV Size from extra space of existing VG

Extend LV Size with new hardDisk

We add new disk /dev/sde to LVM using ‘fdisk ’ command

To do this activity we need to execute the below command.

# fdisk /dev/sde

Type ‘n’ to create new partition

Afer that type ‘p’ to create the primary partition

After that we need to enter first and last cylinder value.

Then type ‘t’ and we will enter the partition id to create LVM . Now we need to enter 8e and press w to save change.

Now our disk is prepared to add our existing LV. We have to follow the below steps.

Create Physical volume

Now we create a Physical volume by executing the following command

# pvcreate /dev/sde

To Check PV we use ‘pvdisplay’ command,

Extend Volume group ‘testvg’ to add /dev/sde

# vgextend testvg /dev/sde

To Verify new VG Size we execute ‘vgdisplay’ command

Extend Logical volume ‘testlv’ we need to follow below command.

# lvextend –L +5G /dev/testvg/testlv

Extend logical volume

Here, ‘-L +5G’ means that the size of LV’testlv’ will increased by 5GB, we can verify the new size by executing ‘lvdisplay’ command.

But the LV Size is not affected.After execute the resize command the new LV Size will be affected.

To resize the filesystem we need to execute the below command.

# resize2fs /dev/testvg/testlv

To verify new LV Size we execute lvdisplay command.

Extend LV Size from extra space of testvg

Lets take an example we have 2 GB extra space in our existing Volume Group ‘testvg’ . we add that extra space to our lv to inctease the size by following the below process.

Extend Logical volume ‘testlv’ execute the below command.

# lvextend –L +2G /dev/testvg/testlv

To resize the filesystem we need to execute the below command.

# resize2fs /dev/testvg/testlv

To verify new LV Size we execute lvdisplay command.

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