How to add New Disk in Linux CentOS 7 Without Rebooting

Increasing disk spaces on the Linux servers is a daily routine work for very system administrator. So, in this article we are going to show you some simple simple steps that you can use to increase your disk spaces on Linux CentOS 7 without rebooting to your production server using Linux commands. We will cover multiple methods and possibilities to increase and add new disks to the Linux systems, so that you can follow the one that you feel comfortable while using according to your requirements.

1) Increasing Disk of VM Guest:

Before increasing the disk volume inside your Linux system, you need to add a new disk or increase the one its has already attached with the system by editing its settings from your VMware vShere, Workstation or any other infrastructure environment that you are using.


2) Check Disk Space:

Run the following command to check the current size of your disk space.

# df -h


# fdisk -l


Here we can see that the total disk size is still the same that is 10 GB while we have already increased it to 50 GB from the back end.

3) Expanding Space without Rebooting VM

Now run the following commands to expand the disk space in the physical volume of the Operating System without rebooting the virtual machine by Re-scanning the SCSI Bus and then adding SCSI Device.

# ls /sys/class/scsi_host/

# echo "- - -" > /sys/class/scsi_host/host0/scan

# echo "- - -" > /sys/class/scsi_host/host1/scan

# echo "- - -" > /sys/class/scsi_host/host2/scan

Check the names of your SCSI devices and then rescan the SCSI buses using below commands.

# ls /sys/class/scsi_device/

# echo 1 > /sys/class/scsi_device/0\:0\:0\:0/device/rescan

# echo 1 > /sys/class/scsi_device/2\:0\:0\:0/device/rescan

That will rescan the current scsi bus and the disk size that we increased from the VM guest settings will be show up as you can see in the below image.


4) New Disk Partition:

Once you are able to see the increased disk space inside your system then the run the following command to format your disk for creating a new partition by following the steps to increase your physical disk volume.

# fdisk /dev/sda


Welcome to fdisk (util-linux 2.23.2) press the 'm' key for help
Command (m for help): m
Command action
a toggle a bootable flag
b edit bsd disklabel
c toggle the dos compatibility flag
d delete a partition
g create a new empty GPT partition table
G create an IRIX (SGI) partition table
l list known partition types
m print this menu
n add a new partition
o create a new empty DOS partition table
p print the partition table
q quit without saving changes
s create a new empty Sun disklabel
t change a partition's system id
u change display/entry units
v verify the partition table
w write table to disk and exit
x extra functionality (experts only)

Command (m for help):

Type the ‘p’ to print the current partition table then create a new primary partition by typing the ‘n’ key and selecting the available sectors. Change the disk type to ‘Linux LVM’ by using ‘t’ command and selecting the code to ‘8e’ or leave as it to its default type that is ’83’.

Now write the table to disk and exit by Entring ‘w’ key as shown.

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.
The kernel still uses the old table. The new table will be used at
the next reboot or after you run partprobe(8) or kpartx(8)


5)Creating Physical Volume:

As indicated above run the ‘partprobe’ or kpartx command so that the tables are ready to use and then create the new Physical Volume using the below commands.

# partprobe

# pvcreate /dev/sda3

To check the newly created volume run the following command to see if the new physical volume has been created and visible. After that we will extend the Volume Group ‘centos’ with the newly create Physical Volume as shown.

# pvdisplay

# vgextend centos /dev/sda3


6) Extending Logical Volume:

Now we will extend the Logical Volume to increase the disk space on it using the the below command.

# lvextend -L +40G /dev/mapper/centos-root

Once you get the successfully increased message, run the command as shown below to extend the size of your logical volume .

# xfs_growfs /dev/mapper/centos-root

The size of the ‘/’ partition has been increased successfully, you can check the size of your disk drives by using the ‘df’ command as shown.


7) Extending Root Partition by Adding New Disk Without Reboot:

This is the second method with but with quite similar commands to increase the size of the Logical volume in CentOS 7.

So, the first step is to Open the setting of your VM guest settings and click on the ‘Add’ new button and proceed to the next option.


Choose the required configuration for the new disk by selecting the size of the new disk and its type as shown in the below image.


Then come to the server side and repeat the following commands to scan your disk devices to the new disk is visible on the system.

# echo "- - -" > /sys/class/scsi_host/host0/scan

# echo "- - -" > /sys/class/scsi_host/host1/scan

# echo "- - -" > /sys/class/scsi_host/host2/scan

List the names of your SCSi devices

# ls /sys/class/scsi_device/

# echo 1 > /sys/class/scsi_device/1\:0\:0\:0/device/rescan
# echo 1 > /sys/class/scsi_device/2\:0\:0\:0/device/rescan
# echo 1 > /sys/class/scsi_device/3\:0\:0\:0/device/rescan

# fdisk -l


Once the new disk is visible run the below commands to create the new physical volume and add it to the volume group as shown.

# pvcreate /dev/sdb

# vgextend centos /dev/sdb

# vgdisplay


Now extend the Logical Volume by adding the disk space on it and then add it to the root partition.

# lvextend -L +20G /dev/mapper/centos-root

# xfs_growfs /dev/mapper/centos-root

# df -h


Managing disk partitions in Linux CentOS 7 is a simple process to increase the disk space of any of your logical volumes by using the steps as described in this article. You don’t need to give your production server’s reboot for this purpose but simply rescan your SCSi devices and expand your desired LVM.

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How to Install OwnCloud 9.0.2 on CentOS 7 / RHEL 7

ownCloud is based on PHP and a SQLite, MySQL, Oracle or PostgreSQL database, so it can run on all platforms that meet these requirements. It provides almost all possibility of functions that are available on commercial suites; it is released under AGPLv3 license, so you can setup own cloud storage server without any additional cost.

Commercial version of ownCloud is also available.

What’s new in ownCloud 9:

It is now easier to keep ownCloud updated with the channel of your choice via the built-in Updater app and our package repositories.
ownCloud Server  brings much improved performance in the areas of syncing, file operations and dealing with parallel requests.
To make ownCloud easier to use, documentation has been massively improved and integrated in the interface.

The following are the list of features available on ownCloud.

Mobile and Desktop Syncing
Share With Anybody
External Storage
Encryption and Security
Versioning and Undelete
Activity Feed
Calendars and Contacts
Collaborative Editing
Play Music, Watch Movies, Store Passwords

Download and Setup:

Run the following shell commands as root to trust the repository.

rpm --import

Run the following shell commands as root to add the repository and install from there.

wget -O /etc/yum.repos.d/ce:stable.repo
yum clean expire-cache
yum install owncloud-files

Allow apache in firewall.

firewall-cmd --permanent --zone=public --add-service=http
firewall-cmd --permanent --zone=public --add-service=https
firewall-cmd --reload

Allow the web server to read and write the files on ownCloud directory.

chown -R apache.apache /var/www/html/owncloud/

Start Apache .

systemctl start httpd.service

Auto start the service at system start-up.

systemctl enable httpd.service


Set SELinux to allow OwnCloud to write the data.

semanage fcontext -a -t httpd_sys_rw_content_t '/var/www/html/owncloud/data'
restorecon '/var/www/html/owncloud/data'
semanage fcontext -a -t httpd_sys_rw_content_t '/var/www/html/owncloud/config'
restorecon '/var/www/html/owncloud/config'
semanage fcontext -a -t httpd_sys_rw_content_t '/var/www/html/owncloud/apps'
restorecon '/var/www/html/owncloud/apps'


The default maximum file size for uploads is 512MB. You can increase this limit by editing .htaccess file.

vi /var/www/html/owncloud/.htaccess

Modify the below entries.

php_value upload_max_filesize 513M
php_value post_max_size 513M


My OwnCloud

That’s All!.

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How to Block Ping (ICMP) Responses in Linux System

Blocking ping responses from system can prevent system from hackers to ICMP flood dos attacks. So it can be a best practice for system security but most of online monitoring systems uses ping requests for monitoring system.
Disable Ping using iptables

You can simply block icmp responses directly from firewall in any Linux systems.

# iptables -A INPUT -p icmp --icmp-type echo-request -j DROP

Block Ping with Kernel Parameter

We can also block ping responses from system by directly updating kernel parameters. In this we can block ping responses temporarily or permanently as below.

Block Ping Temporarily

You can block temporarily block ping responses temporarily using following command

# echo "1" >  /proc/sys/net/ipv4/icmp_echo_ignore_all

Block Ping Permanently

In place of blocking ping temporarily, You can block it permanently by adding following parameter in /etc/sysctl.conf configuration file.

net.ipv4.icmp_echo_ignore_all = 1

Now execute following command to apply settings immediately without rebooting system.

# sysctl -p
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How to Stop and Disable Firewalld on CentOS 7

Firewalld is a complete firewall solution that has been made available by default on all CentOS 7 servers, including Liquid Web Core Managed CentOS 7, and Liquid Web Self Managed CentOS 7. On occasion, perhaps for testing, disabling or stopping firewalld may be necessary. Follow the instructions below to disable firewalld and stop firewalld.

It is highly recommended that you have another firewall protecting your network or server before, or immediately after, disabling firewalld.

Pre-Flight Check
These instructions are intended specifically for stopping and disabling firewalld CentOS 7.
I’ll be working from a Liquid Web Self Managed CentOS 7 server, and I’ll be logged in as root.

Disable Firewalld
To disable firewalld, run the following command as root:

systemctl disable firewalld

Stop Firewalld
To stop firewalld, run the following command as root:

systemctl stop firewalld

Check the Status of Firewalld
And finally, to check the status of firewalld, run the following command as root:

systemctl status firewalld

Wait, you actually wanted to Start and Enable Firewalld on CentOS 7? Then hit our tutorial on: How to Start and Enable Firewalld on CentOS 7!

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How To Upgrade to PHP 7 on CentOS 7


PHP 7, which was released on December 3, 2015, promises substantial speed improvements over previous versions of the language, along with new features like scalar type hinting. This guide explains how to quickly upgrade an Apache or Nginx web server running PHP 5.x (any release) to PHP 7, using community-provided packages.

Warning: As with most major-version language releases, it’s best to wait a little while before switching to PHP 7 in production. In the meanwhile, it’s a good time to test your applications for compatibility with the new release, perform benchmarks, and familiarize yourself with new language features.


Subscribing to the IUS Community Project Repository

Since PHP 7.x is not yet packaged in official repositories for the major distributions, we’ll have to rely on a third-party source. Several repositories offer PHP 7 RPM files. We’ll use the IUS repository.

IUS offers an installation script for subscribing to their repository and importing associated GPG keys. Make sure you’re in your home directory, and retrieve the script using curl:

cd ~
curl '' -o

Run the script:

sudo bash

Upgrading mod_php with Apache

This section describes the upgrade process for a system using Apache as the web server and mod_php to execute PHP code. If, instead, you are running Nginx and PHP-FPM, skip ahead to the next section.

Begin by removing existing PHP packages. Press y and hit Enter to continue when prompted.

sudo yum remove php-cli mod_php php-common

Install the new PHP 7 packages from IUS. Again, press y and Enter when prompted.

sudo yum install mod_php70u php70u-cli php70u-mysqlnd

Finally, restart Apache to load the new version of mod_php:

sudo apachectl restart

You can check on the status of Apache, which is managed by the httpd systemd unit, using systemctl:

systemctl status httpd

Upgrading PHP-FPM with Nginx

This section describes the upgrade process for a system using Nginx as the web server and PHP-FPM to execute PHP code. If you have already upgraded an Apache-based system, skip ahead to the PHP Testing section.

Begin by removing existing PHP packages. Press y and hit Enter to continue when prompted.

sudo yum remove php-fpm php-cli php-common

Install the new PHP 7 packages from IUS. Again, press y and Enter when prompted.

sudo yum install php70u-fpm-nginx php70u-cli php70u-mysqlnd

Once the installation is finished, you’ll need to make a few configuration changes for both PHP-FPM and Nginx. As configured, PHP-FPM listens for connections on a local TCP socket, while Nginx expects a Unix domain socket, which maps to a path on the filesystem.

PHP-FPM can handle multiple pools of child processes. As configured, it provides a single pool called www, which is defined in /etc/php-fpm.d/www.conf. Open this file with nano (or your preferred text editor):

sudo nano /etc/php-fpm.d/www.conf

Look for the block containing listen =, which tells PHP-FPM to listen on the loopback address at port 9000. Comment this line with a semicolon, and uncomment listen = /run/php-fpm/www.sock a few lines below.

; The address on which to accept FastCGI requests.
; Valid syntaxes are:
;   ''    - to listen on a TCP socket to a specific IPv4 address on
;                            a specific port;
;   '[ip:6:addr:ess]:port' - to listen on a TCP socket to a specific IPv6 address on
;                            a specific port;
;   'port'                 - to listen on a TCP socket to all addresses
;                            (IPv6 and IPv4-mapped) on a specific port;
;   '/path/to/unix/socket' - to listen on a unix socket.
; Note: This value is mandatory.
;listen =
; WARNING: If you switch to a unix socket, you have to grant your webserver user
;          access to that socket by setting listen.acl_users to the webserver user.
listen = /run/php-fpm/www.sock

Next, look for the block containing listen.acl_users values, and uncomment listen.acl_users = nginx:

; When POSIX Access Control Lists are supported you can set them using
; these options, value is a comma separated list of user/group names.
; When set, listen.owner and are ignored
;listen.acl_users = apache,nginx
;listen.acl_users = apache
listen.acl_users = nginx
;listen.acl_groups =

Exit and save the file. In nano, you can accomplish this by pressing Ctrl-X to exit, y to confirm, and Enter to confirm the filename to overwrite.

Next, make sure that Nginx is using the correct socket path to handle PHP files. Start by opening /etc/nginx/conf.d/default.conf:

sudo nano /etc/nginx/conf.d/php-fpm.conf

php-fpm.conf defines an upstream, which can be referenced by other Nginx configuration directives. Inside of the upstream block, use a # to comment out server;, and uncomment server unix:/run/php-fpm/www.sock;:

# PHP-FPM FastCGI server
# network or unix domain socket configuration

upstream php-fpm {
server unix:/run/php-fpm/www.sock;

Exit and save the file, then open /etc/nginx/conf.d/default.conf:

sudo nano /etc/nginx/conf.d/default.conf

Look for a block beginning with location ~ \.php$ {. Within this block, look for the fastcgi_pass directive. Comment out or delete this line, and replace it with fastcgi_pass php-fpm, which will reference the upstream defined in php-fpm.conf:

location ~ \.php$ {
try_files $uri =404;
fastcgi_split_path_info ^(.+\.php)(/.+)$;
# fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock;
fastcgi_pass php-fpm;
fastcgi_index index.php;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
include fastcgi_params;

Exit and save the file, then restart PHP-FPM and Nginx so that the new configuration directives take effect:

sudo systemctl restart php-fpm
sudo systemctl restart nginx

You can check on the status of each service using systemctl:

systemctl status php-fpm
systemctl status nginx

Testing PHP

With a web server configured and the new packages installed, we should be able to verify that PHP is up and running. Begin by checking the installed version of PHP at the command line:

php -v


PHP 7.0.1 (cli) (built: Dec 18 2015 16:35:26) ( NTS )
Copyright (c) 1997-2015 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2015 Zend Technologies

You can also create a test file in the web server’s document root. Although its location depends on your server configuration, the document root is typically set to one of these directories:


Using nano, open a new file called info.php in the document root. By default, on Apache, this would be:

sudo nano /var/www/html/info.php

On Nginx, you might instead use:

sudo nano /usr/share/nginx/html/info.php

Paste the following code:



Exit the editor, saving info.php. Now, load the following address in your browser:


You should see the PHP 7 information page, which lists the running version and configuration. Once you’ve double-checked this, it’s safest to delete info.php:

sudo rm /var/www/html/info.php

You now have a working PHP 7 installation.

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