Redhat Enterprise Linux – Network Bonding

Bonding is a feature to combine two or more network interface to form a single, logical “bonded” interface, for redundancy or increased throughput purpose.

We can configure Linux bonding in 7 different modes. The behavior of the bonded interfaces depends upon the mode.

1. Balance-rr (mode 0)

2. Active-backup (mode 1)

3. Balance-xor (mode 2)

4. Broadcast (mode 3)

5. 802.3ad (mode 4)

6. Balance-tlb (mode 5)

7. Balance-alb (mode 6)

Balance-rr (mode 0): Configuring a bonding Channel between eth0 and eth1 using the default mode.

1)# service NetworkManager stop

#chkconfig NetworkManager off

2)Bonding module should be configured and loaded. To enable bonding module, create a bonding.conf file as below.

Note : you can add multiple entries to create multiple bonding channels like bond0, bond1, bond2…etc

# cat > /etc/modprobe.d/bonding.conf

alia bond0 bonding

options bond0 mode=1 miimon=100 

3. Create a configuration file for the bonding channel i.e. bond0, as below

# cat /etc/sysconfig/network-scripts/ifcfg-bond0

DEVICE=bond0
IPADDR=192.168.50.111
NETMASK=255.255.255.0
USERCTL=no
BOOTPROTO=none
ONBOOT=yes
BONDING_OPTS=”mode=0 miimon=100″

4.) Create configuration files for all the interfaces  i.e. eth0 and eth1, which are participating in the bonding channel.

# cat > /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
BOOTPROTO=none
HWADDR=aa:bb:cc:dd:ee:ff  
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no

# cat > /etc/sysconfig/network-scripts/ifcfg-eth1

DEVICE=eth0
BOOTPROTO=none
HWADDR=yy:xx:zz:aa:bb:cc
ONBOOT=yes
MASTER=bond0
SLAVE=yes
USERCTL=no

5. Activating Bonding Channel 

a. With out rebooting

# modprobe bonding

# service network restart

b. with reboot

# reboot

6. Verify that Bonding channel is active, by using the commands

# cat /proc/net/bonding/bond0 
Ethernet Channel Bonding Driver: v3.0.2 (Nov 25, 2012) 

Bonding Mode: adaptive load balancing 
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: aa:bb:cc:dd:ee:ff

Configurable Bonding Parameters:-

max_bonds : specifies the number of bonding devices that can be configured on single bonding driver.

xmit_hash_policy      : Slecect the transmit has policy to use for slave selection in balance-xor and 802.3d modevice. Possible values , layer2 (default) , larer2+3 or layer3+4

arp_interval : Specifies the ARP link monitoring frequency in milli seconds

arp_ip_target : Specifies the IP addresses to use as ARP monitoring peers when arp_interval is > 0. Multiple IP addresses must be seperated by comma. At least one IP addres must be given for ARP monitoring to work. Max. no. of target IPs are 16.

arp_validate : Specifies Whether or not ARP probes and replies should be validated in the active-backup mode. This causes the ARP monitor to examine the incoming ARP requests and replies, and only consider a slave to be up if it is receiving the appropriate ARP traffic. Possible values  

none(0) – default value

active(1) – validate only the active slave

backup(2) – validate only the backup slave

all(3) – validate all slaves

miimon : Specifies the MII link monitoring frequency in milliseconds. A value of 0 disables the MII link monitroing. A value of 100 is recommended.

updelay : specifies the time, in milliseconds, to wait before disabling a slave after a link recovery has been detected.

downdelay : specifies the time, in milliseconds, to wait before disabling a slava after a link failure has been detected.

use_carrier : specifies whether or not miimon shoudl use MII/ETHTOO “ioctls for value of 0 ” or ” netif_carrier_ok() for value 1 ( default value)” functions to determine the link status.

What is a container?

 A native, default zone on the Oracle Solaris 10 OS is called a container. The other containers that run on Oracle Solaris 10 include Oracle Solaris 8 Containers and Oracle Solaris 9 Containers. Many people use the terms "zone" and "container" interchangeably.

how to install JAVA in LINUX?

download  latest version of java and extract it in /usr/local #./jdk-6u14-linux-i586.bin

#which java : display java location

#cd /usr/local
#ln -s jdk1.6.0_14 java : create soft link with name java
#mv /usr /bin/java /usr /bin/java.org
#ln -s /usr/local/java/bin/java  /usr/bin/java
#/usr/bin/java -version : it will display the latest version of java

password expiration extension command for UNIX?

LINUX:-

if password has expired.no need to reset password.we can extend the password.

#chage -d <date year-month-day:current date>  user

solaris:
#usermod -e  <data it has to expire> username

in solaris,suppose to day date is may10th. u have to give as auguest10th. i.e password has extended up to aug 10th. in linux u have to give to day date.

how to synchronize system local time with hwclock by using NTP server in LINUX?

Following is the process to synchronize  local time with hwclock by using NTP server.

• ntpdate
• ntpdate <server name>
• check system date by using #date command.
• #hwclock --show : it will display hwclock
• #ntpstat : communicate with ntp server and display time.
• check which time zoemne has mentioned in server  #cat /etc/sysconfig/clock.

                ls -ltr /etc/localtime
                rm -rf /etc/localtime
                ln -s /usr/share/zoneinfo/America/Denver /etc/localtime
                ls -ltr /etc/localtime
      now check hwclock and system date as same.

•          still if you are facing problem,check  /etc/ntp.con file with ntp server details.

how to bring newly added disk under control of LVM ?

#first check all available disks: fdisk -l
#check pvs and lvs
#create disk partition using : fdisk /dev/sdb
#create physical volume : pvcreate /dev/sdb1
#create volume group : vgcreate mysql_vg /dev/sdb1
#create logical volume : lvcreate -L 20G -n datavol mysql_vg
#make a file system : mkfs.ext4 -m 2 /dev/mysql_vg/datavol
#create a mount point 
#mount the Partition : mount /dev/mysql_vg/datavol  <mount point>  

how to scan LUNS in LINUX with out rebooting server?

first check busing fdisk -l command.
if new luns has not detected.before that take lun id from storage team.it is easy to identify lun.

#powemt config
Assuming that there are two hbas, numbered 0 and 1 :-

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

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

#echo "1" > /sys/class/fc_host/host0/issue_lip
#echo "1" > /sys/class/fc_host/host1/issue_lip
then,

powermt display dev=all | grep "Pseudo"

powermt display dev=all | grep "Logical device"
we can check with lun id provided by storage team.

how to remove logical volume form LVM

unmount the partation : umount  <mount point>

remove logical volume : lvremove <lv name>

check with lvdisplay command,to check status.

vgremove <vg name > : remove volume group

pvremove /dev/sdb1 : remove physical volume

fdsik -l : check the physical partations.