Updating Objects and Virtualization with Dynamics NAV : Virtualization with Dynamics NAV

In simple terms, virtualization means to create a virtual version of a physical resource. The resource could be a physical device such as a physical server, storage device, network or programs, or even operating systems. A simple example could be that of partitioning a hard drive—we take one physical drive and partition it to create two separate hard drives.

Although there can be many detailed categorizations and sub-categorizations of virtualization, it can be broadly classified into five main categories:

• Server virtualization: Consolidating multiple physical servers into virtual servers that run on a single physical server.

• Application virtualization: An application runs on another host from where it is installed in a variety of ways.

• Desktop virtualization: Essentially it's the concept of separating a personal computer desktop environment from the physical machine through a remote server connection. The virtualized desktop is stored on a remote central server and so, when users work from their remote desktop client, all of the programs, applications, processes, and data used are kept and run centrally, allowing users to access their desktops on any light device that need not be as resource rich as the applications would have otherwise required.

• Network virtualization: With network virtualization, a physical network is logically segmented by multiplexing shared access to a single network. Resource components of a virtual network could include switches, VLANs, network storage devices, virtual network containers, and so on.

• Storage virtualization: This is the technique of virtualizing the disk/data storage for our data, which is consolidated to and managed by a virtual storage system.

Advantages of virtualization

The following are the advantages of virtualization:

• Virtualization results in huge savings on hardware, environmental costs, management, and administration of the server infrastructure by consolidating the workloads of several underutilized servers to fewer machines, perhaps a single machine (server consolidation).

• Virtualization is an important concept in building secure platforms by providing secure, isolated playground systems for running untrusted applications.

• Virtual machines can be used to run multiple operating systems simultaneously, different versions, or entirely different systems.

• Virtual machines can provide abstracts of hardware, or hardware configuration that we do not actually have (such as multiple CPUs, SCSI devices, and so on).

• Virtualization can make tasks such as system migration, backup, and recovery easier and more manageable.

• Apart from various other advantages, high availability is one of the many important advantages of a virtualized environment. Let's take an example of high availability with Hyper-V available using new features in Server 2008. Availability means that users can access a system to do their work. With high availability, there is a significant expectation that users will always be able to access the system, as it has been designed and implemented to ensure operational continuity. High availability for Hyper-V is achieved through the use of the Windows Server 2008 Failover Cluster feature. High availability is impacted by both planned and unplanned downtime, and failover clustering can significantly increase availability of virtual machines in both of these categories.

  Virtual machines can be managed by the Failover Cluster, and the Failover Cluster can be used inside of virtual machines to monitor and move the workloads that are hosted in the virtual machine. In order to understand availability, let's take broad categories in planned and unplanned downtime scenarios:

  • Guest availability: Guests that are running Windows Server 2008 can use the Windows Failover Cluster feature to provide high availability for their workloads. There are several advantages to using Windows failover clustering inside of a guest.

  • Virtual machine maintenance: If the configuration of the VM needs to be changed or if the OS or software needs to be updated or changed, the workload can be moved to another node of the cluster and the virtual machine can either be shut down or updated with minimal interruption to the end users.

  • Host machine maintenance: If the physical machine hosting a Hyper-V VM needs maintenance or software updates and other members of the Windows Failover Cluster are located on different Hyper-V hosts, the workload on the VM can be moved to another node of the cluster and VM can be shut down to accommodate the changes or reboots of the physical server.

  • Virtual or Host Machine Failure: If there is a failure of the physical Hyper-V host or the virtual machine guest, the other nodes of the Windows Failover Cluster will detect that the cluster member is no longer responding or participating in the cluster and the surviving nodes will bring online the applications or services that had been running on the failed VM.

Dynamics NAV and application virtualization

Dynamics NAV is widely used today in development environments with various virtualization technologies. Although there's no formal recommendation from Microsoft on the use of virtualization with NAV in production environments, various case studies and tests suggest the use of Dynamics NAV in a virtualized environment with a slight variance in performance. To study in detail how NAV is supported in virtualization environments, let's first look at the compatibility guidance on NAV with various virtualization technologies. The guidance is available on the server catalog website often suggested by the Microsoft support team for versions compatibility.

The following table shows which virtualization technologies are supported with the listed guest OS architectures:

According to the website, VMWare ESX 3.5 update 5 and VM vSphere 4.0 update 1 are not supported as of now.

Guest OS x86(32 Bit) is only supported and x64 is not supported as of now.

But this compatibility guidance website or other sources should be checked for the latest and current compatibility updates.

After having gone through the compatibility guide, let's now review some performance results with NAV on some common processes.

The tests were done on Dynamics NAV 2009 SP1 on Server 2008 as host OS with HyperV. Although the tests are done using Hyper-V only, various sources suggest similar results (testing recommended) using other Hypervisor-based virtualizations such as VMWare, among others.

The scenario used three service tiers with and without HyperV on standard hardware with 75 simulated concurrent users. The tests were done using standard hardware, not high performance machines.

Similar tests scenarios can also be studied in the official hardware and performance guide provided by Microsoft for NAV 2009.

The performance difference was huge in some specific processes, but the average performance declined from anywhere between 8 percent to 40 precent in most processes. The average response time ranged from 300ms to 1100ms without Hyper-V to 330ms to 1500ms with Hyper-V. The processes for which the performance was very different were short processes ranging from 1ms to 20ms.

Although the percentagewise performance was down to an average of 8% to 40%, the actual response time differential was in the range of 30ms to 500ms depending on the process.

This might not be a big deterrent in most businesses but Microsoft Dynamics NAV should not be run in a virtualized environment purely for performance reasons; instead, other factors such as saving on hardware costs, among others, should be strongly considered for a virtualized environment.

Also, other factors such as SQL optimization should be considered. For example, adding two or more cores to the computer running Microsoft Dynamics NAV Server (according to the performance guide) gives a 5 percent gain over two cores.

Server virtualization is supported with NAV 2009 even today. But NAV 2009 R2 and future versions interfaces would allow deployment using Microsoft Application Virtualization (App-V) technology, which is relevant for both on-premise and hosted solutions.