How to Create extra root user account in Linux

Create extra root user account in Linux

********************************

vi /etc/sudoers

testuser ALL=(ALL) NOPASSWD: ALL

*************

after this still we have to use sudo like: (or jst do sudo -s)

#sudo <superuser command>

*************

#usermod -o -u 0 -g 0 <user_name>

*************

#adduser -u 0 -o -g 0 -G 0,1,2,3,4,6,10 -M root2

*************

How to Enable the "root" Account on CentOS or Mac OS X

#sudo passwd root

Enter Password: Changing password for root

New password: Verify password:

How to protect files & folders with password in Linux

only for file protection

gpg  –c  abc.tar

gpg abc.tar

protection for file & Folder both 

zip  –e  -r  <dir name>   <zip dir name which must be same as dir name> 

zip  -e  -r  yy yy

unzip –a yy.zip

Hide a file or folder in Linux

=========================

Just rename the file or folder with prefix dot i.e

Eg:

File name or folder name is hello

#mv  hello  .hello

**********************************************************************

You can password protect a zip file. Proceed as follows:

Create a directory for this experiment, and name it test.

Copy a few files and paste them into this directory so it isn't empty.

Now open a terminal and enter:

$ zip -e -r test test

Enter password:

Verify password:

Delete the directory test.

Now you have a file test.zip which is password protected.

zip with -e option encrypts the contents of the zip archive using a password. This encrypts with standard pkzip encryption which is considered weak.

However, the job of protecting the file is done, because even the root user needs the password to decrypt.

Linux NIC Teaming or NIC Bonding

Linux NIC Teaming or NIC Bonding

*******************************

[root@node1 ~]# cat /etc/modprobe.d/modprobe.conf

alias eth0 e1000

alias eth1 e1000

alias eth2 e1000

alias eth3 e1000

alias bond0 bonding

options bond0 max_bonds=2 miimon=100 mode=1

alias bond1 bonding

options bond1 max_bonds=2 miimon=100 mode=1

[root@node1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-bond0

DEVICE=bond0

IPADDR=192.168.1.11

NETMASK=255.255.255.0

BOOTPROTO=static

ONBOOT=yes

USERCTL=no

IPV6INIT=no

[root@node1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-bond1

DEVICE=bond1

IPADDR=172.24.1.11

NETMASK=255.255.0.0

BOOTPROTO=static

ONBOOT=yes

USERCTL=no

IPV6INIT=no

[root@node1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth0

# Intel Corporation 82540EM Gigabit Ethernet Controller

DEVICE=eth0

BOOTPROTO=static

HWADDR=08:00:27:EA:1C:EC

MASTER=bond0

SLAVE=yes

ONBOOT=yes

USERCTL=no

[root@node1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth1

# Intel Corporation 82540EM Gigabit Ethernet Controller

DEVICE=eth1

BOOTPROTO=static

HWADDR=08:00:27:12:A1:28

MASTER=bond1

SLAVE=yes

ONBOOT=yes

USERCTL=no

[root@node1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth2

# Intel Corporation 82540EM Gigabit Ethernet Controller

DEVICE=eth2

BOOTPROTO=static

HWADDR=08:00:27:32:CD:DE

MASTER=bond0

SLAVE=yes

ONBOOT=yes

USERCTL=no

[root@node1 ~]# cat /etc/sysconfig/network-scripts/ifcfg-eth3

# Intel Corporation 82540EM Gigabit Ethernet Controller

DEVICE=eth3

BOOTPROTO=static

HWADDR=08:00:27:EE:C4:38

MASTER=bond1

SLAVE=yes

ONBOOT=yes

USERCTL=no

[root@node1 ~]# mii-tool

eth0: no autonegotiation, 100baseTx-FD, link ok

eth1: no autonegotiation, 100baseTx-FD, link ok

eth2: no autonegotiation, 100baseTx-FD, link ok

eth3: no autonegotiation, 100baseTx-FD, link ok

[root@node1 ~]# ifconfig -a

bond0     Link encap:Ethernet  HWaddr 08:00:27:EA:1C:EC

          inet addr:192.168.1.11  Bcast:192.168.1.255  Mask:255.255.255.0

          inet6 addr: fe80::a00:27ff:feea:1cec/64 Scope:Link

          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1

          RX packets:2473 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1645 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:236857 (231.3 KiB)  TX bytes:219985 (214.8 KiB)

bond1     Link encap:Ethernet  HWaddr 08:00:27:12:A1:28

          inet addr:172.24.1.11  Bcast:172.24.255.255  Mask:255.255.0.0

          inet6 addr: fe80::a00:27ff:fe12:a128/64 Scope:Link

          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1

          RX packets:581 errors:0 dropped:0 overruns:0 frame:0

          TX packets:53 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:60072 (58.6 KiB)  TX bytes:7215 (7.0 KiB)

eth0      Link encap:Ethernet  HWaddr 08:00:27:EA:1C:EC

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:2243 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1663 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:215657 (210.6 KiB)  TX bytes:222773 (217.5 KiB)

eth1      Link encap:Ethernet  HWaddr 08:00:27:12:A1:28

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:346 errors:0 dropped:0 overruns:0 frame:0

          TX packets:53 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:38572 (37.6 KiB)  TX bytes:7215 (7.0 KiB)

eth2      Link encap:Ethernet  HWaddr 08:00:27:EA:1C:EC

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:235 errors:0 dropped:0 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:21500 (20.9 KiB)  TX bytes:0 (0.0 b)

eth3      Link encap:Ethernet  HWaddr 08:00:27:12:A1:28

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:235 errors:0 dropped:0 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:21500 (20.9 KiB)  TX bytes:0 (0.0 b)

lo        Link encap:Local Loopback

          inet addr:127.0.0.1  Mask:255.0.0.0

          inet6 addr: ::1/128 Scope:Host

          UP LOOPBACK RUNNING  MTU:16436  Metric:1

          RX packets:1770 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1770 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:2020795 (1.9 MiB)  TX bytes:2020795 (1.9 MiB)

sit0      Link encap:IPv6-in-IPv4

          NOARP  MTU:1480  Metric:1

          RX packets:0 errors:0 dropped:0 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

[root@node1 ~]#modprobe bonding

[root@node1 ~]#service network restart

[root@node1 ~]# cat /proc/net/bonding/bond0

Ethernet Channel Bonding Driver: v3.4.0 (October 7, 2008)

Bonding Mode: fault-tolerance (active-backup)

Primary Slave: None

Currently Active Slave: eth0

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: up

Link Failure Count: 0

Permanent HW addr: 08:00:27:ea:1c:ec

Slave Interface: eth2

MII Status: up

Link Failure Count: 0

Permanent HW addr: 08:00:27:32:cd:de

[root@node1 ~]# cat /proc/net/bonding/bond1

Ethernet Channel Bonding Driver: v3.4.0 (October 7, 2008)

Bonding Mode: fault-tolerance (active-backup)

Primary Slave: None

Currently Active Slave: eth1

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth1

MII Status: up

Link Failure Count: 0

Permanent HW addr: 08:00:27:12:a1:28

Slave Interface: eth3

MII Status: up

Link Failure Count: 0

Permanent HW addr: 08:00:27:ee:c4:38

[root@node1 ~]#

add following lines to file

#vim /etc/sysctl.conf

# Gigabit tuning

net.core.rmem_max = 16777216

net.core.wmem_max = 16777216

# net.core.wmem_max = 8388608

net.ipv4.tcp_window_scaling = 1

net.ipv4.tcp_rmem = 4096 87380 16777216

net.ipv4.tcp_wmem = 2096 65535 16777216

net.ipv4.tcp_mem = 98304 131072 196608

net.core.netdev_max_backlog = 250000

net.ipv4.tcp_timestamps = 1

net.ipv4.ip_local_port_range = 1025 61000

# VM pressure fixes

vm.swappiness = 100

vm.inactive_clean_percent = 100

vm.pagecache = 200 10 20

vm.dirty_ratio = 10

vm.dirty_background_ratio = 5

# Security tweaks

net.ipv4.tcp_synack_retries = 3

net.ipv4.tcp_tw_recycle = 1

net.ipv4.tcp_max_syn_backlog = 10240

net.ipv4.tcp_fin_timeout = 30

net.ipv4.tcp_keepalive_time = 1200

What is bonding?

Bonding is the same as port trunking. In the following I will use the word bonding because practically we will bond interfaces as one.

But still...what is bonding?

Bonding allows you to aggregate multiple ports into a single group, effectively combining the bandwidth into a single connection. Bonding also allows you to create multi-gigabit pipes to transport traffic through the highest traffic areas of your network. For example, you can aggregate three megabits ports (1 mb each) into a three-megabits trunk port. That is equivalent with having one interface with three megabits speed.

Where should I use bonding?

You can use it wherever you need redundant links, fault tolerance or load balancing networks. It is the best way to have a high availability network segment. A very useful way to use bonding is to use it in connection with 802.1q VLAN support (your network equipment must have 802.1q protocol implemented).

The best documentation is on the Linux Channel Bonding Project page

I strongly recommend to read it for more details.

Credits: Linux Channel Bonding Project page , Thea

This small howto will try to cover the most used bonding types. The following script (the gray area) will configure a bond interface (bond0) using two ethernet interface (eth0 and eth1). You can place it onto your on file and run it at boot time..

#!/bin/bash

modprobe bonding mode=0 miimon=100 # load bonding module

ifconfig eth0 down # putting down the eth0 interface

ifconfig eth1 down # putting down the eth1 interface

ifconfig bond0 hw ether 00:11:22:33:44:55 # changing the MAC address of the bond0 interface

ifconfig bond0 192.168.55.55 up # to set ethX interfaces as slave the bond0 must have an ip.

ifenslave bond0 eth0 # putting the eth0 interface in the slave mod for bond0

ifenslave bond0 eth1 # putting the eth1 interface in the slave mod for bond0

You can set up your bond interface according to your needs. Changing one parameters (mode=X) you can have the following bonding types:

mode=0 (balance-rr)

Round-robin policy: Transmit packets in sequential order from the first available slave through the last. This mode provides load balancing and fault tolerance.

mode=1 (active-backup)

Active-backup policy: Only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond's MAC address is externally visible on only one port (network adapter) to avoid confusing the switch. This mode provides fault tolerance. The primary option affects the behavior of this mode.

mode=2 (balance-xor)

XOR policy: Transmit based on [(source MAC address XOR'd with destination MAC address) modulo slave count]. This selects the same slave for each destination MAC address. This mode provides load balancing and fault tolerance.

mode=3 (broadcast)

Broadcast policy: transmits everything on all slave interfaces. This mode provides fault tolerance.

mode=4 (802.3ad)

IEEE 802.3ad Dynamic link aggregation. Creates aggregation groups that share the same speed and duplex settings. Utilizes all slaves in the active aggregator according to the 802.3ad specification.

Pre-requisites:

1. Ethtool support in the base drivers for retrieving

the speed and duplex of each slave.

2. A switch that supports IEEE 802.3ad Dynamic link

aggregation.

Most switches will require some type of configuration

to enable 802.3ad mode.

mode=5 (balance-tlb)

Adaptive transmit load balancing: channel bonding that does not require any special switch support. The outgoing traffic is distributed according to the current load (computed relative to the speed) on each slave. Incoming traffic is received by the current slave. If the receiving slave fails, another slave takes over the MAC address of the failed receiving slave.

Prerequisite:

Ethtool support in the base drivers for retrieving the

speed of each slave.

mode=6 (balance-alb)

Adaptive load balancing: includes balance-tlb plus receive load balancing (rlb) for IPV4 traffic, and does not require any special switch support. The receive load balancing is achieved by ARP negotiation. The bonding driver intercepts the ARP Replies sent by the local system on their way out and overwrites the source hardware address with the unique hardware address of one of the slaves in the bond such that different peers use different hardware addresses for the server.

The most used are the first four mode types...

Also you can use multiple bond interface but for that you must load the bonding module as many as you need.

Presuming that you want two bond interface you must configure the /etc/modules.conf as follow:

alias bond0 bonding

options bond0 -o bond0 mode=0 miimon=100

alias bond1 bonding

options bond1 -o bond1 mode=1 miimon=100

Notes:

* To restore your slaves MAC addresses, you need to detach them from the bond (`ifenslave -d bond0 eth0'). The bonding driver will then restore the MAC addresses that the slaves had before they were enslaved.

* The bond MAC address will be the taken from its first slave device.

* Promiscous mode: According to your bond type, when you put the bond interface in the promiscous mode it will propogates the setting to the slave devices as follow:

o for mode=0,2,3 and 4 the promiscuous mode setting is propogated to all slaves.

o for mode=1,5 and 6 the promiscuous mode setting is propogated only to the active slave.

For balance-tlb mode the active slave is the slave currently receiving inbound traffic, for balance-alb mode the active slave is the slave used as a "primary." and for the active-backup, balance-tlb and balance-alb modes, when the active slave changes (e.g., due to a link failure), the promiscuous setting will be propogated to the new active slave.

RHEL/CentOS 6 Bonding

Bonding

Bonding (also known as “Ethernet bonding”) is a computer networking arrangement in which two or more network interfaces on a host computer are combined for redundancy or increased throughput.
mode=0 (Balance-rr) – This mode provides load balancing and fault tolerance.
mode=1 (active-backup) – This mode provides fault tolerance.
mode=2 (balance-xor) – This mode provides load balancing and fault tolerance.
mode=3 (broadcast) – This mode provides fault tolerance.
mode=4 (802.3ad) – This mode provides load balancing and fault tolerance.
mode=5 (balance-tlb) – Prerequisite: Ethtool support in the base drivers for retrieving the speed of each slave.
mode=6 (Balance-alb) – Prerequisite: Ethtool support in the base drivers for retrieving the speed of each slave.

Note: Always append extra configuration in case of a rollback.

Configuring  Bonding

# cd /etc/sysconfig/network-scripts/

# vi ifcfg-bond0

1 2 3 4 5 6 7 8 9 10

DEVICE=bond0 USERCTL=no BOOTPROTO=none ONBOOT=yes IPADDR=10.0.0.10 NETMASK=255.255.0.0 NETWORK=10.0.0.0   TYPE=Unknown IPV6INIT=no

# vi ifcfg-eth0

1 2 3 4 5 6

DEVICE=eth0 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no

# vi ifcfg-eth1

1 2 3 4 5 6

DEVICE=eth1 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no

# vi ifcfg-eth2

1 2 3 4 5 6

DEVICE=eth2 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no

Due to the fact that /etc/modprobe.conf has been deprecated in RedHat / CentOS 6, the process of bonding network interfaces has changed a bit.
Now instead of defining your bond in your /etc/modprobe.conf, you define it in /etc/modprobe.d/bonding.conf

# vi /etc/modprobe.d/bonding.conf

We’ll be using mode=6 (Balance-alb)
Append the following onto the end out your modprobe config file

1 2	alias bond0 bonding options bond0 mode=6 miimon=100

# servive network restart

Mount NTFS file system with read write access in Linux OS

Mount NTFS file system with read write access

Mounting NTFS file system with read write access permissions is a bit more complicated. This involves installation of addition software such as fuse and ntfs-3g. In both cases you probably need to use your package management tool such as yum, apt-get, synaptic etc.. and install it from your standard distribution repository. Check for packages ntfs-3g and fuse. We take the other path which consists of manual compilation and installation fuse and ntfs-3g from source code.

3.1. Install addition software

3.1.1. Fuse Install

Download source code from: http://fuse.sourceforge.net/

wget http://easynews.dl.sourceforge.net/sourceforge/fuse/fuse-2.7.1.tar.gz

Compile and install fuse source code:
Extract source file:

tar xzf fuse-2.7.1.tar.gz

Compile and install

cd fuse-2.7.1
./configure --exec-prefix=/; make; make install

3.1.2. ntfs-3g install

Download source code from: http://www.ntfs-3g.org/index.html#download

wget http://www.ntfs-3g.org/ntfs-3g-1.1120.tgz

Extract source file:

tar xzf ntfs-3g-1.1120.tgz

Compile and install ntfs-3g source code
NOTE: Make sure that you have pkg-config package installed, otherwise you get this error message:

checking for pkg-config... no
checking for FUSE_MODULE... configure: error: FUSE >= 2.6.0 was not found. Either it's not fully
installed (e.g. fuse, fuse-utils, libfuse, libfuse2, libfuse-dev, etc packages) or files from an old
version are still present. See FUSE at http://fuse.sf.net/

cd ntfs-3g-1.1120
./configure; make; make install

3.2. Mount ntfs partition with read write access

mount -t ntfs-3g /dev/sdb1 /mnt/ntfs/

NOTE: ntfs-3g recommends to have at least kernel version 2.6.20 and higher.

linuxconfig.org~# mount -t ntfs-3g /dev/sdb1 /mnt/ntfs/
WARNING: Deficient Linux kernel detected. Some driver features are
         not available (swap file on NTFS, boot from NTFS by LILO), and
         unmount is not safe unless it's made sure the ntfs-3g process
         naturally terminates after calling 'umount'. If you wish this
         message to disappear then you should upgrade to at least kernel
         version 2.6.20, or request help from your distribution to fix
         the kernel problem. The below web page has more information:
         http://ntfs-3g.org/support.html#fuse26

Shell Script to find Greatest and Smallest number

Shell Script to find Greatest and Smallest number (it is Successfully running)

#vi maxminnum.sh
echo "enter size of an array"
read n
#taking input from user
for((i=0;i<n;i++))
do
echo " enter $((i+1)) number"
read nos[$i]
done
#printing the entered number
echo "number entered are"
for((i=0;i<n;i++))
do
echo ${nos[$i]}
done
#main loop
small=${nos[0]}
greatest=${nos[0]}
for((i=0;i<n;i++))
do
#logic for smallest number
if [ ${nos[$i]} -lt $small ]; then
small=${nos[$i]}
#logic for greatest number
elif [ ${nos[$i]} -gt $greatest ]; then
greatest=${nos[$i]}
fi
done
#printing smallest and greatest number
echo "smallest number in an array is $small"
echo "greatest number in an array is $greatest"

:wq!

Shell Script Output:

===============Running Script=======================

#chmod 755 maxminnum.sh       or   #chmod +x maxminnum.sh

#bash maxminnum.sh                or   #sh maxminnum.sh
enter size of an array
10
 enter 1 number
34
 enter 2 number
56
 enter 3 number
87
 enter 4 number
98
 enter 5 number
88
 enter 6 number
77
 enter 7 number
34
 enter 8 number
56
 enter 9 number
76
 enter 10 number
56
number entered are
34
56
87
98
88
77
34
56
76
56
smallest number in an array is 34
greatest number in an array is 98

Menu Driven Program in Bash Shell Script

Menu Driven Program in Bash Shell Script

===============================

while :
do
clear
echo " M A I N - M E N U"
echo "1. Contents of /etc/passwd"
echo "2. List of users currently logged"
echo "3. Present handling directory"
echo "4. Exit"

echo -n "Please enter option [1 - 4]"

read opt

case $opt in

1) echo "************ Conents of /etc/passwd *************";

more /etc/passwd;;

2) echo "*********** List of users currently logged";

who |less;;

3) echo "You are in $(pwd) directory";

echo "Press [enter] key to continue. . .";

read enterKey;;

4) echo "Bye $USER";

exit 1;;

*) echo "$opt is an invaild option. Please select option between 1-4 only";

echo "Press [enter] key to continue. . .";

read enterKey;;

esac

done
=======================================================

Output:

 M A I N - M E N U
1. Contents of /etc/passwd
2. List of users currently logged
3. Prsent handling directory
4. Exit
Please enter option [1 - 4]

How to generate DSA & RSA SSH Key in Linux and Windows

How to generate DSA & RSA SSH Key

********************************************

 

Procedure to Generate DSA (Digital Signature Algorithm) or RSA Key Pair in Windows

=====================================================================

PuTTY is an SSH client for Windows that will use to generate your SSH keys. PuTTY is a free open-source terminal emulator that functions much like the Terminal application in Windows environment.

 

When you install the PuTTY client, you also install the PuTTYgen utility. PuTTYgen is what you will use to generate your SSH key for a Windows

 

To generate an SSH key with PuTTYgen, follow these steps:

 

Open the PuTTYgen program from “C:\Program Files\PuTTY”

For Type of key to generate, select SSH-2 RSA.

Click the Generate button.

Move your mouse in the area below the progress bar. When the progress bar is full, PuTTYgen generates your key pair.

Type a passphrase in the Key passphrase field. Type the same passphrase in the Confirm passphrase field. You can use a key without a passphrase, but this is not recommended (but here please generate key without passphrase)

Click the Save public & private key button to save the public & private key.

 

Right-click in the text field labeled Public key for pasting into OpenSSH authorized_keys file and choose Select All.

Right-click again in the same text field and choose Copy.

 

Procedure to Generate DSA (Digital Signature Algorithm) or RSA Key Pair in Unix/Linux

=====================================================================

Use ssh-keygen command as follows:

 

$ ssh-keygen -t dsa

 

Output:

Enter file in which to save the key (/home/<username>/.ssh/id_dsa):  Press [Enter] key

Enter passphrase (empty for no passphrase): myPassword

Enter same passphrase again: myPassword

Your identification has been saved in /home/<username>/.ssh/id_dsa.

Your public key has been saved in /home/<username>/.ssh/id_dsa.pub.

The key fingerprint is:

04:be:15:ca:1d:0b:1e:e2:a7:e5:de:96:4a:b1:a6:01 <username>@<domainname>.com

 

Steps:

a) Please enter a passphrase and confirm the same.

b) The public key is written to /home/<username>/.ssh/id_dsa.pub

c) The private key is written to /home/<username>/.ssh/id_dsa

 

Note:

====

DSA is more secure than RSA & faster in signing "signature generation" but slower in verifying (slower for validation, slower when encrypting) i.e. authenticates slower (recommended)

 

RSA is less secure than DSA & slower in signing "signature generation" but faster in verifying (faster for validation, faster when encrypting) i.e. authenticates faster

 

Public key is made available to everyone via a publicly accessible repository or directory

Private Key must remain confidential to its respective owner. (It is important that not to share your private key for Security concern)

LVM Expansion/Extend the File System in Linux

LVM Expansion/Extend the File System in Linux

Note:   Current Size of VG (Volume Group) DISKVG08907 is 59.99G & we have to extend upto 80G

There are two methods to expand file system online in Linux: (recommended on LVM Version 2)

======================================================

#lvm version  (command to check LVM Version)

#lvextend -L 79.99G /dev/DISKVG08907/app         (do not mention any sign while rounding up)

(Above command will round up the logical volume app to 79.99 GB)

#resize2fs /dev/DISKVG08907/app                         

(Above command will resize the logical volume app)

Or

#lvextend -L +20G /dev/DISKVG08907/app           (please remember to mention + sign while adding)

(Above command will add 20GB more in logical volume app)

#resize2fs /dev/DISKVG08907/app

(Above command will resize the logical volume app)

======================================================

Below is the example to extend file system online

bash-3.2# hostname

LinuxServer1

(Status before expanding /app file system)

======================================================

bash-3.2# df –HT  /app

Filesystem                                           Type     Size   Used  Avail Use% Mounted on

/dev/mapper/DISKVG08907-app     ext3      64G   461M    60G   1% /app

bash-3.2# fdisk -l

Disk /dev/sda: 16.1 GB, 16106127360 bytes

255 heads, 63 sectors/track, 1958 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1          33      265041   83  Linux

/dev/sda2              34        1958    15462562+  8e  Linux LVM

Disk /dev/sdb: 85.8 GB, 85899345920 bytes

255 heads, 63 sectors/track, 10443 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1               1        7832    62910508+  8e  Linux LVM

bash-3.2#

bash-3.2# pvs

  PV                  VG                   Fmt      Attr      PSize                PFree

  /dev/sdb1    DISKVG08907             lvm2    a-          59.99G                       0

bash-3.2# vgs

  VG        #PV #LV #SN Attr   VSize  VFree

  DISKVG08907   1   1   0 wz--n- 59.99G    0

bash-3.2# lvs

  LV      VG                               Attr      LSize   Origin Snap%  Move Log Copy%  Convert

  app     DISKVG08907            -wi-ao  59.99G

======================================================

bash-3.2# fdisk /dev/sdb

The number of cylinders for this disk is set to 10443.

There is nothing wrong with that, but this is larger than 1024,

and could in certain setups cause problems with:

1) software that runs at boot time (e.g., old versions of LILO)

2) booting and partitioning software from other OSs

   (e.g., DOS FDISK, OS/2 FDISK)

Command (m for help): p

Disk /dev/sdb: 85.8 GB, 85899345920 bytes

255 heads, 63 sectors/track, 10443 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1               1        7832    62910508+  8e  Linux LVM

Command (m for help): n

Command action

   e   extended

   p   primary partition (1-4)

p

Partition number (1-4): 2

First cylinder (7833-10443, default 7833): (press enter)

Using default value 7833

Last cylinder or +size or +sizeM or +sizeK (7833-10443, default 10443): (press enter)

Using default value 10443

Command (m for help): p

Disk /dev/sdb: 85.8 GB, 85899345920 bytes

255 heads, 63 sectors/track, 10443 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1               1        7832    62910508+  8e  Linux LVM

/dev/sdb2            7833       10443    20972857+  83  Linux

Command (m for help): t

Partition number (1-4): 2

Hex code (type L to list codes): 8e

Changed system type of partition 2 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/sdb: 85.8 GB, 85899345920 bytes

255 heads, 63 sectors/track, 10443 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1               1        7832    62910508+  8e  Linux LVM

/dev/sdb2            7833       10443    20972857+  8e  Linux LVM

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.

Syncing disks.

bash-3.2# partprobe /dev/sdb       

(Partprobe is a program that informs the operating system kernel of partition table changes, by requesting that the operating system re-read the partition table)

bash-3.2# fdisk -l

Disk /dev/sda: 16.1 GB, 16106127360 bytes

255 heads, 63 sectors/track, 1958 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *           1          33      265041   83  Linux

/dev/sda2              34        1958    15462562+  8e  Linux LVM

Disk /dev/sdb: 85.8 GB, 85899345920 bytes

255 heads, 63 sectors/track, 10443 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System

/dev/sdb1               1        7832    62910508+  8e  Linux LVM

/dev/sdb2            7833       10443    20972857+  8e  Linux LVM

bash-3.2# pvcreate /dev/sdb2

  Physical volume "/dev/sdb2" successfully created

bash-3.2# pvs

  PV         VG           Fmt  Attr PSize  PFree

  /dev/sda2  vg00         lvm2 a-   14.62G  5.88G

  /dev/sdb1  DISKVG08907 lvm2 a-   59.99G     0

  /dev/sdb2               lvm2 a-   20.00G 20.00G

bash-3.2# vgs

  VG           #PV #LV #SN Attr   VSize  VFree

  DISKVG08907   1   1   0 wz--n- 59.99G    0

  vg00           1   5   0 wz--n- 14.62G 5.88G

bash-3.2# vgextend -v DISKVG08907 /dev/sdb2

    Checking for volume group "DISKVG08907"

    Archiving volume group "DISKVG08907" metadata (seqno 2).

    Wiping cache of LVM-capable devices

    Adding physical volume '/dev/sdb2' to volume group 'DISKVG08907'

    Volume group "DISKVG08907" will be extended by 1 new physical volumes

    Creating volume group backup "/etc/lvm/backup/DISKVG08907" (seqno 3).

  Volume group "DISKVG08907" successfully extended

bash-3.2# lvextend -L 79.99G /dev/DISKVG08907/app

  Rounding up size to full physical extent 79.99 GB

  Extending logical volume app to 79.99 GB

  Logical volume app successfully resized

bash-3.2# resize2fs /dev/DISKVG08907/app

resize2fs 1.39 (29-May-2006)

Filesystem at /dev/DISKVG08907/app is mounted on /app; on-line resizing required

Performing an on-line resize of /dev/DISKVG08907/app to 20969472 (4k) blocks.

The filesystem on /dev/DISKVG08907/app is now 20969472 blocks long.

(Status after expanding /app file system)

======================================================

bash-3.2# df –HT /app

Filesystem                                           Type     Size   Used Avail   Use% Mounted on

/dev/mapper/DISKVG08907-app     ext3      85G   465M    80G   1%   /app

bash-3.2# pvs

  PV         VG           Fmt  Attr PSize  PFree

  /dev/sda2  vg00         lvm2 a-   14.62G  5.88G

  /dev/sdb1  DISKVG08907 lvm2 a-   59.99G     0

  /dev/sdb2  DISKVG08907 lvm2 a-   20.00G 20.00G

bash-3.2# vgs

  VG           #PV #LV #SN Attr   VSize  VFree

  DISKVG08907   2   1   0 wz--n- 79.99G 20.00G

bash-3.2# lvs

  LV      VG           Attr   LSize   Origin Snap%  Move Log Copy%  Convert

  app     DISKVG08907 -wi-ao  79.99G

======================================================

bash-3.2# cd /app     

bash-3.2# du -sh *                 (check & confirm /app data)

16K     lost+found

259M    file1

bash-3.2# cat /etc/fstab         (check entry in /etc/fstab for /app file system)

/dev/DISKVG08907/app   /app                    ext3    defaults        0 0

Created by: Yogesh Anuvadia