Tag: initramfs

This guide will help you prepare your CentOS 6 server for a migration from on-premise to Microsoft Azure cloud. It can be a bit tricky to get everything to work correctly and personally I didn’t find Microsofts guides to be great so I write this post to help you with the steps that is needed to migrate your old CentOS 6 machine to the cloud.

What you need to configure

• Install Azure Linux Agent
• Network Configuration
• Hyper-V Drivers Configuration
• Serial Console Configuration

How to do it

Install Azure Linux Agent

Note: You will probably need to fix mirror configuration since CentOS 6 is EOL. Instructions can be found on the following link.

• Alternative 1
  yum install WaLinuxAgent
  
• Alternative 2
  cd /tmp
wget http://olcentgbl.trafficmanager.net/openlogic/6/openlogic/x86_64/RPMS/WALinuxAgent-2.2.45-1.el6.noarch.rpm
yum localinstall WALinuxAgent-2.2.45-1.el6.noarch.rpm

Network Configuration

The network interface needs to be configured to use DHCP and you need to add the hyper-v drivers to the interface. You can either do it by configuring your existing networki interface (eth0) or create a new one:

1. Create a configuration file for the interface
vim /etc/sysconfig/network-scripts/ifcfg-eth0

NAME="eth0"
DEVICE="eth0"
BOOTPROTO=dhcp
ONBOOT=yes

Save the file with :wq

2. Map the networking card to the Hyper-V drivers by appending the following line to the 70-persistent-net.rules file.

vim /etc/udev/rules.d/70-persistent-net.rules

#For Azure
SUBSYSTEM=="net", ACTION=="add", DRIVERS=="hv_netvsc", ATTR{type}=="1", KERNEL=="eth*", NAME="eth0"

Save the file with :wq

Hyper-V Drivers Configuration

1. Add Hyper-V drivers to Dracut
   
   vim /etc/dracut.conf
   
add_drivers+=" hv_vmbus hv_netvsc hv_storvsc nvme ena xen_blkfront xen_netfront mptbase mptscsih mptspi "
   
2. Update Initramfs by running the following command:
   
   dracut --force -v
   
3. Verify that the Hyper-V modules have been loaded
   
   lsinitrd | grep hv

Serial Console Configuration

Azure uses ttyS0 for serial connection so we need to add it to our configuration.

1. First add ttyS0 to secureetty by appending the following
   
   vim /etc/secureetty
   #add
ttyS0
   
2. Configure grub
   
   vim /boot/grub/grub.conf
   
   #add below configuration to kernel
   rootdelay=300 console=ttyS0 earlyprintk=ttyS0
   
   #also remove
   rhgb quiet crashkernel=auto
   
3. Configure sysconfig/init
   
   vim /etc/sysconfig/init
   
   #Edit ACTIVE_CONSOLES to look like (make sure to use “”):
   ACTIVE_CONSOLES="/dev/tty[1-6] /dev/ttyS0"
   
   Also make sure to configure:
   timeout=15
serial --unit=0 --speed=115200
terminal --timeout=5 serial console
   

Now you are ready for a migration to Microsoft Azure. I hope you found this guide helpful and that you will succeed with your cloud transformation.

Note: If you are running CentOS 7 I also have a guide for preparing your server for Azure.

// Rickard Carlsson