Sunday, December 16, 2012

Using scripts to automate VMware Site Recovery Manager workflows & recovery steps!

While I am trying to cope up with projects, new VMware products, training and new initiatives for the VMware community, I quickly thought of coming back to the audience and talk about something which I have discussed before in one of my post and share my experience around that.

Well, I am talking about an article which I wrote on Guest IP Customization on VMware SRM. I would suggest you read that first here before reading this to make more sense out of what we are trying to achieve with this post. Here is the link -  Things to Know About Guest IP Customization in VMware Site Recovery Manager!

Coming back to where I left. We know that certain operating systems, mostly Unix based might not support OS Customization, because of which we are unable to use the Guest IP Customization option in the SRM workflow. This feature allows us to insert a new IP address using the OS API's on a virtual machine at the time of Test Recovery or Disaster Recovery workflow execution. If the OS does not support IP customization then you would have to manually change the IP address on the recovered virtual machine on the DR site, this will impact the overall RTO (Recovery Time Objective) to resume services on the DR site. Though this should not impact a Test Drill much, however this method is prone to human errors and can be painful to execute at the time of disaster.

VMware SRM gives a great feature which can be used to achieve the desired automation and agility for recovering VM's with the required IP settings for Guest OSes which do not support customization. If you ever notice the recovery workflow, you would see that you are able to add pre-power on and post-power on commands to a recovery workflow. These commands can then either talk to a central repository of scripts which can be created in the SRM server or on the recovered virtual machine itself. These commands can be called if you select the respective recovery plan which recovers the virtual machines in question. The screenshot below shows how this window looks like in the SRM recovery workflow:-



In this post we will learn how to use the option "COMMAND ON RECOVERED VM". Here is the situation.

SCENARIO==> You have a virtual machine protected using SRM which is running Oracle Linux. Once this VM gets recovered on the DR site during test recovery or disaster recovery, you want the IP address and other settings to change as soon as the VM comes up on the DR site. Since Guest IP Customization will not work on Oracle Linux you would get the following error if you try to use that method - "Error: The Guest operating system "oracleLinux64Guest" is not supported." How will we solve this issue?

SOLUTION==> To solve this issue we would use the Command on Recovered VM feature of SRM workflow. Here is how you navigate to this window:-

1
Click Recovery Plans in the left pane, and select the recovery plan which has the VM in question.
2
Click the Virtual Machines tab.
3
Right-click the virtual machine and click Configure.
4
Select Pre-Power On Steps or Post Power On Steps in the left pane, and click Add.
5
Select Command on Recovered VM.
6
In the Name text box, type a name for the step.
"Command to call IP Address Change Script."

7
In the Content text box, type the commands for the step to run.
/bin/sh<space>/etc/network-scripts/changeip.sh  (I will share the content of the script changeip.sh in a moment)

8
(Optional) Modify the Timeout setting.
9
Click OK to add the step to the recovery plan.
10
Click OK to reconfigure the virtual machine to run the command before or after it powers on.

Here is the screenshot from my server:-





Here is how my script chnageip.sh looks like:-



#!/bin/bash
#################################################################
# Injecting network files for DR environment
/bin/cp -p /etc/network-scripts/network /etc/sysconfig/network 
/sbin/init 6
#End of script.

Let me describe this script. I am copying the files which I have already kept on the Virtual Machine on my primary site with the new IP settings on the following location - /etc/network-scripts/network. These files are replicated to the DR VM image automatically as a part of my replication plan, whether storage based or vSphere Replication.

With this script I am copying the 'network' file which has all the new settings to the /etc/sysconfig/ which will replace the existing IP settings of the Linux machine to the new IP address which we have defined in our DR Network file. After that the VM would reboot to power on with the new settings.

Similar to this script you can do a bunch of things by calling such scripts on the recovered VM's, such as:-

a) Change any other OS settings such as name, IP, network settings etc.
b) Run cron jobs or schedule tasks.
c) Run configuration files to make changes in an application configuration.
d) Do wonders ;-)


Well now when you run this recovery plan, your VM will power on on the DR site and then as soon as the VMware tools is up on the VM, SRM workflow will call this script and the script will change the network settings of the VM as scripted by you automatically. Automation and agility at its best. :-)

You might have questions about rights to run this script etc.. Remember VMware Tools is used here, so the script should have the rights same as the user account which was used to install VMware Tools, normally its domain admin on 'Windows' and root on 'Linux' OSes.

Well that's all for this time, I hope this would help you get things going on SRM and use the amazing options which SRM provides you to automate stuff. In my upcoming article, I would speak about how to use the option of using "Command on SRM server".

Do let me know if you have any questions or comments. Hope this helps..

2 comments:

  1. Image automatically as a part of my replication plan, whether storage based.
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  2. I found this blog very helpful. Disaster recovery tools are really very helpful for data recovery.

    ReplyDelete