Wednesday, September 27, 2017

How to Increase the size of a Linux LVM by adding a new disk

How to Increase the size of a Linux LVM by adding a new disk

This post will cover how to increase the disk space for a VMware virtual machine running Linux that is using logical volume manager (LVM). Firstly we will add a new disk to the virtual machine and then extend the original LVM over this additional space. Basically we will have two physical disks but just one volume group and one logical group that is using the space on both disks together. With this method there is no down time for the virtual machine.

As there are a number of different ways to increase disk space I have also posted some different methods here:
Important Notes: Be very careful when working with the commands in this article as they have the potential to cause a lot of damage to your data. If you are working with virtual machines make sure you take a snapshot of your virtual machine beforehand, or otherwise have some other form of up to date backup before proceeding. It could also be worth cloning the virtual machine first and testing out this method on the clone.
Throughout my examples I will be working with a VMware virtual machine running Debian 6, this was set up with a 20gb disk and we will be adding a new 20gb disk for a total LVM size of 40gb.
Although my examples make use of virtual machines, this method would work with a physical server as well if you have added a new physical disk in and want to use that to expand the LVM.

Identifying the partition type

As this method focuses on working with LVM, we will first confirm that our partition type is actually Linux LVM by running the below command.
fdisk -l
fdisk of newly added disk
As you can see in the above image /dev/sda5 is listed as “Linux LVM” and it has the ID of 8e. The 8e hex code shows that it is a Linux LVM, while 83 shows a Linux native partition. Now that we have confirmed we are working with an LVM we can continue. For increasing the size of a Linux native partition (hex code 83) see this article.
Below is the disk information showing that our initial setup only has the one 20gb disk currently, which is under the logical volume named /dev/mapper/Mega-root – this is what we will be expanding with the new disk.
Disk free newly added disk
Note that /dev/mapper/Mega-root is the volume made up from /dev/sda5 currently – this is what we will be expanding.

Adding a new virtual hard disk

First off we add a new disk to the virtual machine. This is done by right clicking the virtual machine in vSphere, selecting edit settings and then clicking the “Add…” button which is used to add hardware to the virtual machine.
Select hard disk and click next.
VMware add virtual disk
Select create a new virtual disk and click next.
VMware add virtual disk
Select the disk size you want to add, I will be using 20gb as previously mentioned. I have also selected to store the disk with the virtual machine, it will store on the same datastore as the virtual machines files, this will be fine for my test purposes. Click next once complete.
VMware add virtual disk
Select next on the advanced options page.
VMware add virtual disk
Review everything and click finish once you have confirmed the settings.
VMware add virtual disk
You will then see the new disk under the hardware devices tab and it will be labelled with (adding) which means it will not apply until you click OK, so click OK to complete the process.
VMware add virtual disk

Detect the new disk space

In my test for this example, as soon as I added the additional disk in through VMware it displayed through “fdisk -l” for me, you can see the second disk labelled /dev/sdb (I have cropped out the information on /dev/sda1 to make it less cluttered here). It is also worth noting that it shows as not containing a valid partition table, we are about to set this up.
fdisk of newly added disk
This may not however be the case for you, to avoid reboot you may need to rescan your devices, you can try this with the below command. Note that you may need to change host0 depending on your setup.
echo "- - -" > /sys/class/scsi_host/host0/scan
If you have issues detecting the new disk, just perform a reboot and it should then display correctly.

Partition the new disk

We now need to partition the new /dev/sdb disk so that it can be used, this is done by using fdisk.
fdisk /dev/sdb
This should provide us with the below prompt, the inputs I have entered in are shown in bold.
‘n’ was selected for adding a new partition.
[email protected]:~# fdisk /dev/sdb
Command (m for help): n
‘p’ is then selected as we are making a primary partition.
Command action
   e   extended
   p   primary partition (1-4)
As this is a new disk, we do not yet have any partitions on it so we will use partition 1 here.
Partition number (1-4): 1
Next we press the enter key twice, as by default the first and last cylinders of the unallocated space should be correct.
First cylinder (1-2610, default 1): "enter"
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-2610, default 2610): "enter"
Using default value 2610
‘t’ is selected to change to a partitions system ID, in this case we change to ’1′ automatically as this is currently our only partition.
Command (m for help): t
Selected partition 1
The hex code ’8e’ was entered as this is the code for a Linux LVM which is what we want this partition to be, as we will be joining it with the original Linux LVM which is currently using /dev/sda5.
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)
‘w’ is used to write the table to disk and exit, all changes that have been done will be saved and then you will be exited from fdisk.
Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.
By using “fdisk -l” now you will be able to see that /dev/sdb1 is listed, this is the new partition created on our newly added /dev/sdb disk and it is currently using all 20gb of space.
fdisk after partition created

Increasing the logical volume

Next we will use the pvcreate command to create a physical volume for later use by the LVM. In this case the physical volume will be our new /dev/sdb1 partition.
[email protected]:~# pvcreate /dev/sdb1
  Physical volume "/dev/sdb1" successfully created
Now we need to confirm the name of the current volume group using the vgdisplay command. The name will vary depending on your setup, for me it is the name of my test server. vgdisplay provides plenty of information on the volume group, I have only shown the name and the current size of it for this example.
[email protected]:~# vgdisplay
  --- Volume group ---
  VG Name               Mega
  VG Size               19.76 GiB
Now using the vgextend command, we extend the ‘Mega’ volume group by adding in the physical volume of /dev/sdb1 which we created using the pvcreate command just before.
[email protected]:~# vgextend Mega /dev/sdb1
  Volume group "Mega" successfully extended
Using the pvscan command we scan all disks for physical volumes, this should confirm the original /dev/sda5 partition and the newly created physical volume /dev/sdb1
[email protected]:~# pvscan
  PV /dev/sda5   VG Mega   lvm2 [19.76 GiB / 0    free]
  PV /dev/sdb1   VG Mega   lvm2 [19.99 GiB / 19.99 GiB free]
  Total: 2 [39.75 GiB] / in use: 2 [39.75 GiB] / in no VG: 0 [0   ]
Next we need to increase the logical volume with the lvextend command (rather than the physical volume which we have already done). This means we will be taking our original logical volume and extending it over our new disk/partition/physical volume of /dev/sdb1.
Firstly confirm the name of the logical volume using lvdisplay. The name will vary depending on your setup.
[email protected]:~# lvdisplay
  --- Logical volume ---
  LV Name                /dev/Mega/root
  LV Size                18.91 GiB
The logical volume is then extended using the lvextend command. We are extending the original logical volume of /dev/Mega/root over the newer /dev/sdb1
[email protected]:~# lvextend /dev/Mega/root /dev/sdb1
  Extending logical volume root to 38.90 GiB
  Logical volume root successfully resized
If you like you can then run vgdisplay and lvdisplay again to confirm the size of the volume group and logical volume respectively, I have done this and I now have the following.
  LV Size                38.90 GiB
  VG Size                39.75 GiB
However if you run a “df” command to see available disk space it will not have changed yet as there is one final step, we need to resize the file system using the resize2fs command in order to make use of this space.
[email protected]:~# resize2fs /dev/Mega/root
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/Mega/root is mounted on /; on-line resizing required
old desc_blocks = 2, new_desc_blocks = 3
Performing an on-line resize of /dev/Mega/root to 10196992 (4k) blocks.
The filesystem on /dev/Mega/root is now 10196992 blocks long.
Alternatively if you’re running the XFS file system (default as of RedHat/CentOS 7) you can grow the file system with “xfs_growfs /dev/Mega/root”.
Rather than resizing the file system manually, you could instead use the -r option of the lvextend command which will automatically resize the file system to make use of the additional disk space.
The resize took a minute or so to complete (it will depend on the disk speed and size), running the “df” command now shows the correct disk space for /dev/mapper/Mega-root
Disk free on expanded LVM


We have now increased the total disk space on the virtual machine by first adding a new virtual disk through VMware, created a new partition out of this newly unallocated space within the guest OS, turned it into a physical volume, extended the volume group, then finally extended the original logical volume over the newer physical volume resulting in overall disk space being increased successfully. This method allows for disk space upgrade with no down time, my virtual machine was not shut down or rebooted at all during this process. This is a very useful technique for upgrading disk space on production servers that can not go down.

found at:

Friday, July 14, 2017

Fail2ban block 404 scan and invalid method in request on Apache server

Fail2ban block 404 scan and invalid method in request on Apache server

1. Create filter


failregex = [[]client <HOST>[]] File does not exist: *
                   [[]client <HOST>[]] Invalid method in request *
ignoreregex =

2. Add new jail


enabled = true
port = http,https
filter = apache-404
action  = iptables-multiport[name=apache-404,port="80,443"]
logpath = /var/log/httpd/error_log
#you can add email notification as well
action  = iptables-multiport[name=apache-404, port="http,https", protocol=tcp]
          sendmail-whois[name=apache-404, [email protected], [email protected], sendername="Server-Fail2Ban"]

bantime = 172800
maxretry = 2
findtime = 86400   ; 1 day

3. If everything is ok, you can test it

with command:
 fail2ban-regex /var/log/httpd/error_log /etc/fail2ban/filter.d/apache-404.conf

outcome should be like this:

Running tests

Use   failregex filter file : apache-404, basedir: /etc/fail2ban
Use         log file : /var/log/httpd/error_log
Use         encoding : UTF-8


Failregex: 138 total
|-  #) [# of hits] regular expression
|   1) [132] [[]client <HOST>[]] File does not exist: *
|   2) [6] [[]client <HOST>[]] Invalid method in request *

Ignoreregex: 0 total

Date template hits:
|- [# of hits] date format
|  [146] (?:DAY )?MON Day 24hour:Minute:Second(?:\.Microseconds)?(?: Year)?

Lines: 146 lines, 0 ignored, 138 matched, 8 missed
[processed in 0.03 sec]

|- Missed line(s):
|  [Mon Jul 10 05:07:58 2017] [error] [client] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /x
|  [Tue Jul 11 12:27:28 2017] [error] [client] script '/var/www/html/command.php' not found or unable to stat
|  [Wed Jul 12 04:00:18 2017] [error] [client] request failed: error reading the headers
|  [Thu Jul 13 07:12:54 2017] [error] [client] client sent HTTP/1.1 request without hostname (see RFC2616 section 14.23): /
|  [Thu Jul 13 18:05:54 2017] [error] [client] script '/var/www/html/index.php' not found or unable to stat

Friday, June 2, 2017

How To Find Out Dell Service Tag on Centos

How To Find Out Dell Service Tag on Centos

The following command will only display service tag:
dmidecode -s system-serial-number

a little bit more information

dmidecode -t 1

if dmidecode is missing just install it

yum -y install dmidecode

Tuesday, March 14, 2017

How to install KVM Synergy on Raspberry Pi 2

How to install KVM Synergy on Raspberry Pi 2

At first install all missing libraries:

apt-get install gcc cmake libx11-dev libxtst-dev curl libcurl3 libcurl4-gnutls-dev qt4-qmake

download the newest version from


Now tricky part which is true for version Synergy 1.8.8

1. extract files and go inside synergy/ext
2.  unpack files
unzip ./ -d ./gmock-1.6.0
unzip ./ -d ./gtest-1.6.0

tar -xzf openssl-1.0.2.tar.gz

3. make new dir inside synergy root folder
mkdir /home/pi/synergy/openssl

4. Copy folder openssl from /home/pi/synergy/ext/openssl-1.0.2/include/openssl to root folder of synergy

cp -a /home/pi/synergy/ext/openssl-1.0.2/include/openssl/. /home/pi/synergy/openssl

5. If you want to play and fix symlinks - go ahead, the easiest way is to copy crypto folder
to folder above synergy

cp -a /home/pi/synergy/ext/openssl-1.0.2/crypto/. /home/pi/crypto

5. go to  /home/pi/synergy/ and run
  ./ conf -g1
  ./ build

if there any errors from ld use

ld -lssl --verbose

and check folders and symlinks.

and run again 
  ./ build

when finished it could be errors

[100%] Linking CXX executable ../../../../../bin/unittests
[100%] Built target unittests
Going back to:
 Make GUI command: make -w
Entering dir: src/gui
make: Entering directory '
make: *** No targets specified and no makefile found. Stop.
make: Leaving directory '
Going back to:
Error: make -w failed with error: 512

No worries.

6. copy from synergy bin folder

cp -a ./bin/. /usr/bin

7. To start automatically

7.1 create startup script



killall synergyc
sleep 1
export DISPLAY=:0 && synergyc -d INFO -n pi -l /var/log/synergy.log

exit 0

where is your synergy server`s IP.


edit /etc/xdg/lxsession/LXDE-pi/autostart
add to the end of line

8. Start synergy and enjoy!


Thursday, March 2, 2017

How to clean DB from old logs in Magento 1.x

How to clean DB from old logs in Magento 1.x

Using MySQL

truncate log_customer;
truncate log_quote;
truncate log_summary;
truncate log_summary_type;
truncate log_url;
truncate log_url_info;
truncate log_visitor;
truncate log_visitor_info;
truncate log_visitor_online;
login to shell(SSH) 
go with root/shell folder.

execute the below command inside the shell folder
php -f log.php clean
enter this command to view the log data's size
php -f log.php status
This method will help you to clean the log data's very easy way.

Monday, February 27, 2017

Dell web Drac - how to install centos

Dell web Drac - how to install centos

wget -q -O - | bash

yum -y install srvadmin-all

edit to adjust settings:
mcedit /opt/dell/srvadmin/sbin/

to START: /opt/dell/srvadmin/sbin/ start

check if console is running on port 1311

netstat -tulpn | grep 1311

access via https://<ip address>:1311/OMSALogin?msgStatus=null

to STOP:

/opt/dell/srvadmin/sbin/ stop

Wednesday, February 15, 2017

How to restart network interfaces in Raspberry Pi 'service networking restart'

How to restart network interfaces in Raspberry Pi

If you use command service networking restart there will be warn message and sometimes eth0 interface will not come.

To fix it please add auto eth0 into /etc/network/interfaces

[email protected]:~# service networking restart
 [warn] Running /etc/init.d/networking restart is deprecated because it may not re-enable some interfaces ... (warning).
[ ok ] Reconfiguring network interfaces...done.

Monday, February 13, 2017

How to force time sync on Raspberry Pi

How to force time sync on Raspberry Pi

sudo /etc/init.d/ntp stop
sudo ntpd -q -g
sudo /etc/init.d/ntp start

Tuesday, January 24, 2017

Fake screen saver on Raspberry PI

Fake screen saver on Raspberry PI

If you want to make fake screen saver to cover display you can use "feh" to do it.

setup root cron:

17 16 * * * su - pi -c '/usr/bin/export DISPLAY=:0 && /usr/bin/timeout 120 /usr/bin/feh -Y -x -q -D 5 -B black -F -Z -z -r /media/pic/'

so It will activate screen saver for 120 minutes, displaying pictures from/media/pic folder starting at 16:17 everyday


Internet Storm Center Infocon Status

Internet Storm Center Infocon Status
Internet Storm Center Infocon Status