In this tip, I'll focus on backup alternatives for a standalone VMware 3.0.1 environment and a method of performing backups to allow for easy restoration of this type of virtual environment. It will detail the processes of both file level and raw virtual machine file backup alternatives, and will give examples of how to configure and set up the backups for each of these backup methods.
Two running virtual machines
Virtual machine file level backup
There isn't much choice with the configuration in Figure 1, but to install backup agents on each of the virtual machines and to use the same backup process that is used for the physical server layer in the environment, as in Figure 2 below.
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Figure 2. Virtual machine client-based backup flow
Virtual machine raw file backup
File level backups are great, but it could happen that a drive fails and you need to get the entire virtual machine restored to a new server. With file level backups, the process for restoring a virtual machine would be:
This is very time consuming, and the server could still experience issues because of domain membership or other special tweaks that may have been made and/or not applied correctly.
The process for restoring a virtual machine's raw files is as follows:
This process is much less time consuming and will have the failed virtual machine up and running in a fraction of the time of the file restore method.
The following process can be used to back up the raw virtual machine files from the ESX server and to insure a pristine backup of your virtual machine files. The trick to backing up the raw virtual machine files while the virtual machines are running is to use the integrated snapshot capabilities of the VMware ESX server. The snapshot command performs the following to the target virtual machine(s):
To perform a snapshot of a virtual machine, you need to ensure that the VMware tools have been installed and are running on the target virtual machine. VMware tools have program modules that interact with the virtual machine's operating system and issue commands to dump memory and freeze any disk writes during the snapshot process.
Before taking the snapshot. Since the delta and swap files won't be backed up, you first perform a directory list and pipe the output to a file in order to script the backup process. Issue the following command to create this file:
Create the snapshot of the virtual server (VM1). Execute the following command from the console of the ESX server:
Figures 3a and 3b show directory listings of the raw virtual machine disk files before and after the snapshot command is issued. Note that in the second listing there are some new delta files created to hold any new disk or memory writes.
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Figure 3a. Pre-snapshot directory listing
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Figure 3b. Post-snapshot directory listing
Back up the virtual machine files. Now that the virtual machine is snapped, you can back up the virtual machine files. As noted in the environment overview, we have set up OpenSSH services on the backup server to securely copy the raw virtual machines files from the ESX server to the backup server. This eliminates the need to put a backup agent on the ESX server, minimizes the time to transfer the files, and minimizes the length of time that the load is placed on the ESX server.
Back up all files in the virtual machine's directory, excluding delta or snapshot files. Remember the file created prior to the snapshot–use this file with the SFTP command to transfer all of the pre-snapshot virtual machine files.
To perform the backup:
Note that with this configuration of the network layer of the ESX environment, you will use the management console network interface for this copy, and not the Virtual Machine Ethernet interface. This eliminates any possibility of affecting virtual machine performance due to network card utilization. Figure 4 is a graphical representation of the snapshot-based backup flow utilized by this process.
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Figure 4. Snapshot-based backup flow
Commit changes from the delta files. Once the backup is complete, commit any changes (writes) that have been placed in the delta files back into the original VMDK files. To do this, run the following command, which commits the changes from the delta files back into the VMDK files, and then deletes the snapshot and delta files from the disk:
That's it. Your raw files are now on the backup server, which can be backed up to tape or replicated to your DR site for safe keeping.
Perl script for the raw file backup
I've written a perl script that will perform this entire raw file backup process. Just download the file from the following link and save it in the /tmp directory of the ESX server.
Download the Perl script text document.
Disclaimer: This script is presented as-is. The writer, SearchServerVirtualization.com and TechTarget and/or Forsythe are not responsible for any potential damage the script may cause ether in it's current state or if modified by the reader. The script has been tested in a lab environment but is not utilized for production use.
The command line to execute this script is:
Recommended third-party backup tool
One of the best third party tools to perform RAW virtual machine file backups is esxRanger from Vizioncore. A separate server is required to host this application, so this solution may involve additional hardware and software expenses. Information on esxRanger.
esxRanger Professional is the recognized industry-standard backup and restore solution for virtualized environments, and continues to lead the way in establishing disaster recovery standards for VMware Infrastructure 3 users. Administrators can schedule regular backups of either the full image, or just the differential, at appropriate intervals while the virtual machine is still running. Images can be stored either locally in the SAN or sent as compressed files over a WAN to remote locations to support disaster recovery strategies. esxRanger Professional also enables restore of individual files efficiently with an explorer tree through which users can easily identify and "grab" needed files.
More backup instructions to come
The next chapter of How to backup VMware 3.0.1will discuss backup methods for SAN-connected VMware ESX servers with Virtual Center as a management point. It will review technologies such as SAN-based snapshots, consolidated backup, and replication techniques for these types of environments. Stay tuned!
About the authors:
James Davidge, solutions architect at Forsythe Solutions Group, possesses over 19 years of experience in enterprise strategy, analysis, design and implementation of Microsoft, Citrix and virtualization technologies. Davidge overseas assessment, design, and implementation planning phases of large scale project to insure delivery of enterprise class solutions to Forsythe's customers.
James E. Geis is director of integrated solutions development for Forsythe. Geis developed Forsythe's unique information management framework—the roadmap Forsythe uses for information management, storage and server consulting engagements. He currently is focused on developing solutions to address the impact of virtualization on computing technology and the data center.
