Guide to virtualization adoption – Part 4

In the previous article of this series we performed the last planning phase of our virtualization adoption project, the ROI calculation, discovering real costs behind project.

Now we finally enter in the first operational phase: the Physical to Virtual (P2V) migration of physical machines we recognized as good candidates for virtualization.

Candidates’ recognition has been discussed in the first part of this series, being responsible in providing mandatory data for subsequent capacity planning phase.

As we’ll see moving contents of a physical server inside a virtual machine often is a complex technical operation which requires time and costs money.

Physical to Virtual migration

Moving the whole content of a physical computer from its disks to a virtual machine is much more than simply copying files and folders from the starting location to a new position.

Virtual hardware presented by a virtual machine is always different from the one available on the original server and immediately after migration, at first reboot, operating system kernel recognizes new devices and look for drivers to handle them.

In the effort of adjusting itself for the new equipment a kernel not founding appropriate drivers stops to work completely, never reaching operational status.

Depending on operating system this adjustment implies more or less complexity.

Microsoft Windows is the most problematic operating system to move and it requires a helper to seamless fit new hardware.

A P2V migration tool passes to kernel needed drivers and initializes them at the right moment and in the right order, so that it can boot correctly and not show the freighting Blue Screen of Death (BSOD).

In Linux the adjustment is much easier and real experts would be able to perform it without commercial tools, but it’s greatly annoying and time consuming.

Also a manual operation wouldn’t be able to automate the remaining part of the process which involves interaction with the target virtualization platform.

In fact P2V migration tools not only have the responsibility to move data from source computer to target virtual machine and to accommodate the migration, but must be also able to create a new virtual machine with opportune virtual hardware, power it on and install required performance enhancement tools from vendor.

Market leader in this segment of the virtualization industry are PlateSpin and VMware, but other notable competitors exist, like Leostream and HelperApps.

Price of P2V migration tools is often considered very high by newcomers who relate them only to the mere operation to be achieved, without considering, for example, all costs related to unexpected errors in configurations where the physical server has been rebuilt from scratch in a virtual machine.

While in many cases the perception is wrong, PlateSpin is the first company approaching a new way to knock down potential customers’ diffidence: since September 2006 their P2V migration tool is available for rent, proposing a reasonable price per conversion even for smaller projects.

In any case an alternative approach exists: today several virtualization experts and enthusiasts offer free P2V migration tools but while they are good for converting few servers, at the moment no one is really able to scale for use in large conversion projects.

Customers usually discover very fast that amount of time spent to fix these tools when a technical issue appears is much more expensive than the cost per conversion in commercial solutions.

A needful add-on of modern P2V migrations tools is capability to interact with candidates’ recognition and capacity planning products.

Integration between these tools allows speedup of virtual migrations, since every just converted virtual machine can be immediately moved inside the most unloaded host server.

At the moment of writing PlateSpin is the only one offering such service, allowing its P2V solution, PowerConvert, to integrate with its PowerRecon discovery tool.

Desirable plus

A big plus when approaching P2V migration tools is considering their capability to perform the opposite process: a Virtual to Physical (V2P) migration.

While initially there is a prevalent need to consolidate machines, once embraced virtualization it’s easy turn to it for solving several different problems.

The huge administrative effort of deploying new workstation for employees, for example, could be greatly reduced if IT manager would be able to configure an ideal virtual machine and then inject it in brand new hardware.

Today this is partially mitigated with the help of disk cloning utilities like Symantec Save & Restore (formerly Ghost), but these solutions present a couple of severe limitations: they depend on hardware configuration so the same image cannot be restored on a different server, and any modification to the desired configuration implies saving a new master image.

The first limitation is being addressed these days by disk image companies like Acronis, which enhanced traditional cloning tools to restore images on different hardware, supporting also virtual machines, but in general a P2V migration tool also capable to do V2P operations could be the best choice.

Another feature we should look at when approaching a P2V migration product is its capability to perform the so called Virtual to Virtual migration.

A V2V migration moves OSes and their data between virtual machines of different vendors, taking care of differences at the host level and dissimilar virtual hardware.

As soon as multiple hypervisor will find their place in datacenters, bigger companies will have to address multi-vendor management and a simple way to move applications from a product to another.

Once again PlateSpin is leader here, already supporting V2V migrations back and forth between VMware, Microsoft and Virtual Iron virtualization products.

Avoiding downtime

Even the most efficient P2V migration tool has a big limit: it makes the physical machine unusable during the whole process.

The migration time is directly proportional to the size of local storage and network speed: on average a physical machine with a 72GB disk can takes up to 30 minutes for moving through a standard Ethernet link.

This could translate in a very expensive services downtime, which in case of mission critical environments or where a Service Level Agreement (SLA) is in place is not an option.

Luckily P2V technology is evolving and PlateSpin is already able to offer a live migration feature, completely avoiding the downtime.

This much desirable process is possible thanks to a special technique which handle copy of all files, including open and locked ones.

At the moment live migration is only available for Windows physical server but the company will add Linux support in the future.

A future of automation

In a near future candidates’ recognition, capacity planning and P2V/V2P/V2V migration tools will lose their original connotation becoming an intelligent, automated and autonomous service, dedicated to around the clock virtual datacenter optimization.

In perfect automation the candidates’ recognition component would scan 24 hours a day the whole datacenter, looking for underutilized physical server and overloaded virtual machines.

Every time one appears it would pass the report to the capacity planning component, which would suggest the best location where to migrate them: if a physical server is underutilized it has to be converted in a virtual machine, if a virtual machine is overloaded it has to be moved on a less busy host or converted back in a physical machine.

These orders would be passed to the migration component which would perform them seamless, without downtime.

At a point the whole environment will be completely liquid, changing its shape depending of every minute workload. And we’ll not even be able to distinguish if our services are served by a virtual or physical machine.

In our next appointment we’ll see the second, critical operational phase: the enterprise management, where we’ll have to face several challenges, including resources handling and monitoring, infrastructure automation and disaster recovery.

This article originally appeared on SearchServerVirtualization.