With virtualization, you can restore the OS and application as a
single unit, more simply and much more efficiently.
Server virtualization breaks the dependencies between the
operating system and the server hardware. The OS communicates
with the “virtual hardware” provided by the software virtualization layer. The virtualization layer effectively makes the virtual
machine hardware-independent. The virtual hardware seen by the
operating system looks the same regardless of what x86 hardware
is actually underneath the virtual machine.
Utilizing a physical-to-virtual (P2V) tool will help in creating
virtual machines that are identical to their physical server equivalents. Virtualization software encapsulates an entire server into a
set of files containing OS and data volumes as well as configuration files simplifying the components needed to recover a server.
This set of files is the virtual machine (VM).
Virtual machines intrinsically possess two qualities that are
beneficial to DR:
• Hardware independence. Virtual machines are isolated from the
underlying physical hardware. This characteristic of the virtualization
makes it simpler to move VMs between physical systems.
• Encapsulation. Virtual machines are encapsulated into a set of files.
Let’s look at the scenario in Figure 2 (above) where we restore
physical servers to virtual machines.
In this example, we can use one single physical ESX server
on the right to recover seven physical servers on the left. The
back-up and recovery process remains the same as in a physical-to-physical scenario, and it still uses the same backup server and
Figure 2: Converting seven physical servers to one physical virtual host
storage media that were used in a physical-to-physical server
back-up scenario. When there’s a need to recover a system, you
can use this archived virtual machine template and have it up and
running in minutes, with applications and backup/recovery agent
already installed. The great value of server virtualization is seen
in how much faster and easier it is to stand up a recovered server.
Once the virtual server is powered on, the data restore process
will be identical to the restore process in the physical-to-physical
An increased benefit can be achieved by implementing the virtualization in production. The added benefits are:
1. Production servers are already virtual ( i.e.the VMDK file already
exists, alleviating the need to perform a P2V every time a system
change is made).
2. Restoring a VM is equivalent to a complete system restore including
data reducing RTO.
Traditional disaster recovery plans require many manual,
complex steps to perform bare-metal hardware recovery.
Virtualization simplifies this environment. Hardware configuration, firmware, operating system, and application installation
become data stored in just a few files (VMDks) on your SAN.
You can simply protect these files using your back-up or replication software, and you’ve protected the entire system. These
files can then be recovered to any hardware without requiring
any changes because virtual machines are hardware-independent.
With hardware independence, you can repurpose existing servers
for disaster recovery rather than needing to buy duplicate servers for DR. In this approach to recovering IT infrastructure, the
focus moves from machines to a more holistic view that focuses
on capacity, can be dynamically added or removed, and can be
turned on instantly in the event of a disaster. So now you can have
a “real” recovery rather than a “virtual” nightmare.
Richard Dolewski is chief technology officer and vice president of business
continuity services for W TS. Dolewski is a certified systems integration specialist, disaster recovery planner, and is globally recognized as a subject
matter expert for business continuity for IBM iSeries and i5 environments.