In principle, server virtualisation makes preserving business continuity during electrical service interruptions significantly easier, by enabling data centers to move virtual machines onto unaffected host servers elsewhere on the network. In reality, however, managing that process is harder than it sounds.
VMware, Microsoft, Citrix and other server virtualisation software vendors all offer ‘live migration’ products that can swiftly transfer virtual machines from one host server to another for load balancing purposes, or when the original server experiences operational problems or requires maintenance. However, none of those systems include built-in functionality for responding to power outages.
Furthermore, most power protection systems for virtualised server environments come with their own command console. As a result, technicians must use one tool for virtualisation management and a separate one for power management. This weakens their productivity and can delay their response time during utility failures.
Deploying modern power management software significantly eases the complexities of keeping critical applications continuously available during power outages.
For starters, some such solutions integrate closely with leading virtualisation management products, including VMware vCenter Server, Microsoft SCVMM and Citrix XenCenter. That enables technicians to view, monitor and administer not only physical and virtual servers but Uninterruptible Power Systems (UPSs) and other power devices through a single console.
The newest power management solutions can also automatically and transparently move virtual machines from host servers impacted by an electrical outage to unaffected servers elsewhere within the servercluster.
Migrating virtual machines into cloud computing data centers
Looking to increase their efficiency, agility and scalability, businesses today are rapidly adopting cloud computing technologies. In the very near future, the most sophisticated power management solutions will be equipped to help organisations capitalise on cloud computing’s benefits more easily by enabling them to migrate virtual machines into the public portion of a hybrid cloud automatically during power failures, using similar tools and processes they employ when moving virtual servers onto in-house servers.
Data Centers that take advantage of this capability will be free to choose between two different kinds of public cloud infrastructure:
- Platform as a Service (PaaS) solutions provide online access to computing resources and programming tools that developers can use to create and host cloud-based applications.
- Infrastructure as a Service (IaaS) solutions offer infrastructure resources such as storage space and processing power over the Web.
Major PaaS providers typically rely heavily on open source software. Consequently, advanced power management solutions that are optimised for ease of integration with open source environments will be best positioned to take advantage of this powerful new failover capability.
Preserving data integrity
Keeping critical workloads operational is a data center’s top priority during power outages. Preventing data corruption is essential as well, however, and sometimes shutting down servers is the only way to meet that goal.
Data Centers have long relied on a combination of UPSs and power protection software to shut down servers in an orderly fashion during utility outages. Server virtualisation, however, makes safeguarding data during power failures significantly more complicated.
The challenges
When a virtualised data center loses power, technicians must shut down not only their physical servers but the virtual machines running on those host servers as well. Additionally, they must execute the many steps in that process in a specific sequence, often in the face of intense time pressure. For example, they must shut down virtual machines before physical ones, and core devices - such as domain controllers and shared storage arrays - after the servers that depend on them.
The solutions
Companies can overcome these challenges in several ways:
- Download open source management code. Pre-written, open source operating system code for shutting down servers gracefully and in the correct sequence during power failures is being developed and distributed via websites such as Network UPS Tools. By downloading, installing and customising such code, data center managers can equip their infrastructure to shut down servers in the proper order when utility/server power becomes unavailable. This solution offers an easy yet extremely powerful and highly configurable power management option to organisations that use and customise Linux or other open source solutions, a category that includes most operators of cloud computing data centers.
- Deploy advanced power protection software. Though power protection applications enable organisations to shut down servers in an orderly manner during utility failures, most such systems support physical devices only. The latest and most sophisticated power protection solutions, however, support virtual machines, as well as hosts such as VMware ESX, Microsoft Hyper-V, Citrix XenServer and Red Hat KVM. Consequently, they can be configured with the aid of the virtualisation management system to shut down both physical and virtual servers in pre-defined sequences that minimise exposure to data loss.
- Add automated scripts to advanced power protection software. Many advanced power protection solutions enable users to create scripts that automatically respond to specific alarms in a predefined manner. Companies can use such scripts to augment their power protection system’s built-in functionality in sophisticated ways. For example, technicians could extend UPS battery runtime by creating a script that automatically shuts down virtual machines running non-critical workloads early in a power outage and then consolidates the remaining virtual machines onto a smaller number of host servers.
Within the span of a few years, server virtualisation has progressed from promising new technology to data center mainstay. Along the way, it has armed IT and facilities managers with potent new tools for maintaining business continuity during electrical failures while making preserving data integrity during power outages more complicated.
The latest power management solutions position companies to take full advantage of server virtualisation’s rewards while mitigating its risks by enabling data center managers to migrate virtual machines onto unaffected host devices automatically during utility service interruptions.
They also equip IT and facilities managers to shut down physical servers gracefully when such measures are unavoidable. Companies should therefore view advanced power management software as an essential component of any well designed server virtualisation environment.
This article is by Michael Mallia, senior product line manager, distributed power quality, Asia Pacific for Eaton Electrical. It originally appeared in the June issue of IT Brief.