Server Virtualization: Branching Out of the Data Center

Improving Branch Office Infrastructure Efficiency


Multisite organizations are reducing the number of servers in their branch offices by moving applications to the data center. Yet, they continue to place a few essential applications locally because of performance, survivability, or compliance requirements. By making use of server virtualization, these lean branch offices can increase utilization of local infrastructure, reduce application downtime and recovery time, and shorten the time needed to deploy local applications while lowering infrastructure and operating costs.


The rapid growth of server virtualization outside the corporate data center is another indicator of the technology's appeal. Cloud-based services, virtual desktops, and virtualized disaster recovery sites are all made possible by server virtualization. Increasingly, the virtualization technology is also finding its way into the branch office.
Server consolidation, energy savings, and rapid server provisioning are the main benefits of bringing virtualization into the branch office. However, to get the most value, the use cases for the technology must reflect the distinct requirements of remote locations. 
 From the Data Center to the Branch Office
Economies of scale are achieved by packing a large number of x86 servers into a small number of large data centers. The resulting per-server cost reduction has been the primary driver behind data center consolidation. But large data centers are more complex to manage, consume significant amounts of energy, and require sophisticated capacity planning to account for unexpected loads. Server virtualization addresses all these challenges by inserting a thin layer of software (hypervisor) between the server hardware and the operating system. The hypervisor provides virtual hardware containers for hosting applications and operating systems (virtual servers) as shown in Figure 1. Virtual servers can be provisioned more quickly than their physical counterparts; require less space, power, and cooling than multiple physical servers; and can be cloned, moved, or clustered on demand and without service interruption.
 A hypervisor imposes the following set of attributes on virtual servers that traditional x86 servers lack:

 Isolation: A virtual server is confined to one container and unaware of other virtual servers.

 Multiplicity: A virtual server shares hardware concurrently with other virtual servers.

 Abstraction: A virtual server is hardware independent and can run on various platforms.

 Encapsulation: A virtual server stores its complete point-in-time execution state in a file.


Enabling New Capabilities in the Branch Office Through Server Virtualization

Server virtualization brings many new features to the data center that a traditional server cannot provide, such as live virtual server migration, dynamic resource allocation, live CPU and memory increases, and distributed software switches. The small hardware footprint of the lean branch office has limited the use of such features. Nonetheless, a number of new capabilities offered by server virtualization can improve server uptime and failure recovery time and automate server provisioning in the branch office.


A typical lean branch office implements the disaster recovery process either by storing backups on a local storage device with periodic archival to tape or by sending them to a data center for storage and tape archival. A growing number of branch offices rely on continuous data protection by replicating, snapshotting, or mirroring data to a local storage device. Regardless of where the data resides and how frequently it is backed up, two fundamental techniques are used to copy and restore the data:


Block-based disk copying with full-system restoration: This method provides the fastest full-system backup and restore operations, low performance overhead during backups, and full recovery of the server. However, it is an all-or-none approach that requires large storage capacity, individual files cannot be restored, and the restore target must be identical to the original server.


File-based file system copying with data and configuration restoration: This method provides backup and restore operations at the individual file level, platform-independent restoration, and flexibility to adapt the configuration for the restoration target. However, the backup and restore operations take longer, performance overhead is higher during backup, and a server cannot be fully recovered.



A typical lean branch office has a significantly different server infrastructure than a data center, but despite the differences, multisite organizations have much to gain by deploying server virtualization in their branch offices. The virtualization technology helps meet common branch-office challenges, and it introduces new capabilities not available with traditional servers. The main benefits of virtualization in the branch office include:


• Lower infrastructure and operating costs

• Less application downtime and faster response time and failure recovery time

• Faster time to deployment for applications 



Author: Anonymous

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