Another major benefit of server virtualization is the ability to
shift running virtual servers between physical hosts to balance load and
allow for maintenance windows. You can also use snapshots of virtual
servers to keep a moment-in-time copy of a running server prior to
making changes such as software updates. If something goes wrong, you
can simply return to the snapshot, and the affected server will be
running as if you had never touched anything. Clearly, this approach can
save significant time and aggravation.
If you haven’t already moved down the virtualization road, fear
not: More options are available now than ever before, and any time is
the right time to get started.
1. Start Small on Your Desktop or Laptop
Although server virtualization has certainly taken the server room by
storm, you also have many ways to bring virtualization into the office
on a smaller scale--namely, on your desktop or laptop.
Generally, modern desktop and laptop PCs have a surprising amount
of resources that go unused when the system is performing little tasks
such as email reading or Web browsing. If you find that you have the
need to run a different operating system from time to time (say, to
support a legacy application), you could fire up a virtual desktop on
your local system and forgo the physical installation.
This
arrangement is especially useful when you encounter
application-incompatibility issues stemming from running older code on
newer operating systems. To give it a shot for free, you can download VirtualBox for the PC.
2. Set Up a Small, Possibly Free, Lab
If you’ve retired servers recently, they may be a good platform for
you to begin building a virtualization lab. The key is to make sure that
they have several gigabit network interfaces, and as much RAM as you can fit
in them. Virtualization tends to be lighter on CPU resources but
heavier on RAM, especially if you use a virtualization method that
doesn’t employ RAM page sharing to squeeze more space out of physical
RAM.
If you don’t happen to have spare servers handy, you can pick up a
new cheap server (again with plenty of RAM) to test with. If you’re
feeling ambitious, you can even build one from spare parts you might
have lying around. In a lab setting, this machine can serve as a proof
of concept, but you shouldn’t run it in production.
As for the choice of virtualization software, you can try them all
out on a lab system. Armed with several hard drives, you can install
VMware ESXi, Microsoft Hyper-V, Citrix XenServer, or Red Hat RHEV on one
disk apiece, and simply boot to one disk at a time to see which
software fits your needs the best. All of these packages are available
either as free instances or as trials with evaluation periods of 30 or
more days.
3. Build Your Own Shared Storage
When
you're working with virtualization frameworks that have multiple
physical host servers, you’ll need some form of shared storage to fully
realize the benefits of virtualization. For instance, if you want to be
able to migrate virtual servers between physical hosts, the storage for
those virtual servers must reside on a shared device that each host can
access.
Some virtualization arrangements can address a variety of storage
protocols, such as NFS, iSCSI, and Fibre-Channel. For lab or testing
purposes, you can simply add several hard drives to a Windows or Linux
system, share them with NFS or iSCSI, and bind your lab servers to that
storage. If you want a more complete “homegrown” approach, give
open-source storage options, such as FreeNAS, a try. This software offers a simple way to add a variety of storage to a lab or production network, using cheap hardware.
4. Spend Time in the Lab
Armed with some form of shared storage and at least two physical host
servers, you have the basis of a full virtualization platform ready to
go. If you’re evaluating several different packages, try each of them
out for a week or so. Make sure to step through all of the features
important to your needs, such as live virtual server migrations,
snapshots, virtual server cloning and deployment, and high availability.
You may also have the ability to try out production workloads in
the lab to get a feel for how the setup will perform in the real world.
You might build a database server and use a backup of a real data set to
run some reports, or use a Web server benchmarking tool to measure the
performance of a Web application server. This practice will not only
familiarize you with the day-to-day functions of the virtualization
platform but also give you some insight as to what resources your
virtual servers may need when they enter production.
5. Keep the Lab, Even When You Begin Production
After all this, you’ve likely settled on the arrangement you want to use in production. You’ve gotten a feel for the management tools, and you've mapped out how you want to proceed with the real deal. Now is not the time to dismantle the lab, however.
Once you’ve started procuring new hardware for the production
infrastructure, you’ll want to reference settings you've made in the lab
to ensure that the virtual servers you plan to deploy will be able to
handle the tasks assigned to them.
Furthermore, after you’ve completed the production build, you can
use the lab to test new functionality, updates, and beyond, which will
only bolster the stability and reliability of the production platform.
By(Pcworld.com)