What is a Private Cloud?

Confusion about what a private cloud is

There is still a significant amount of confusion about what a private cloud is and whether or not an organization has deployed one in their environment.  This confusion is understandable since there is such a disparity in how various organizations define a private cloud.

The most common misconception I see is an organization deploying a server virtualization platform on a handful of servers and perhaps a management tool and thinking they have a fully functional private cloud.

While a virtualization platform is a key component of a private cloud it is most definitely not the whole thing. There are a few key features that most definitions agree on. Nearly every description includes features such as resource pooling, self-service, elasticity, pay-for-usage and abstraction of computing resources from the infrastructure used to deliver those resources. Let's take a look at each of these features to help understand how a private cloud is so much more than a server virtualization platform.

Resource Abstraction

One of the underlying features of a private cloud that many organizations do have in place, at least to some extent is resource abstraction. A server virtualization platform is a good example of resource abstraction. The customer or end user does not necessarily know the details of the underlying hardware. They just know they need and have been allocated resources X, Y and Z to run their application.

Resource Pooling

In a private cloud your key hardware - compute, network and storage - are pooled and and abstracted. This allows the storage to be broken into dynamically provisioned units which can be scaled as needed.

This allows the user to request resources which satisfy requirements for a specific application without needing to know the specifics of the underlying hardware. The details of the hardware should be irrelevant to the request as long as they meet the performance requirements of the application or service. 


The ability for customers (internal or external) to request, configure and manage IT services through a portal which allows automated provisioning is a key feature that are lacking in many "private clouds". This is an interesting feature to be lacking because it has been around in one form or another for nearly as long as x86 server virtualization.


An environment is considered elastic when resources can be quickly and easily expanded or contracted through automation or a workflow allowing IT services to be scaled up or down nearly immediately to meet business requirements.

Examples of this functionality include automated powering on and off of virtualization hosts as demand requires or automated provisioning of storage based on demand.


Resource usage metering so that customers/users can pay for what they actually consume is the key point of a pay-for-usage model.


Truly implementing a private cloud means much more than just deploying a server virtualization platform in their data center. A private cloud gives you a way to completely transform the way IT services are delivered to your business.

There are several companies which offer ways to deploy these features in your environment. I will leave it to you to decide who's solution is right for you. 


What's New in Private Cloud with the new Microsoft R2 Release

Windows Server 2012 R2 - New and Changed Functionality

Shared Virtual Hard Disk

Hyper-V in Windows Server 2012 R2 enables virtual machines to share VHDX files. 

This feature allows us to more easily build cluster virtual machines. Shared virtual hard disks allow multiple virtual machines to access the same VHDX file, which is a convenient way to provide shared storage for Windows Failover Clustering. the shared VHDX files can be hosted on highly available CSVs or SMB based Scale-Out File Server file shares.

Generation 1 and 2 virtual machines are supported in a guest failover cluster which uses a shared virtual hard disk. 

Resize virtual hard disk

Hyper-V storage now supports resizing of virtual hard disks while the virtual machine is running. 

Resizing virtual hard disks while the virtual machine is running allows administrators to perform configuration and maintenance on virtual hard disks when the virtual machine the virtual hard disk is attached to is online and/or the virtual hard disk is in use. 

Online virtual hard disk resizing is only available for VHDX files which are attached to a SCSI controller.  VHDX files that are attached to an IDE controller are not supported for resizing.

When expanding a virtual hard disk while it is online functionality is very similar to performing an offline expansion. After expanding the virtual hard disk it is necessary to log on to the virtual machine and expand the volume within the virtual machine to make use of the additional space on the virtual hard disk. In Windows this can be done through Disk Manager.

Similarly when shrinking a virtual hard disk the amount it can be shrunk is limited by the size of the volume currently in use on the virtual hard disk inside the virtual machine.  The Hyper-V Manager user interface shows the minimum disk size available for shrinking a virtual hard disk.

Storage Quality of Service

Storage Quality of Service (QoS) enables the administrator to manager storage throughput for virtual hard disks which are accessed by their virtual machines.  

This feature allows the administrator to specify the maximum and minimum I/O loads in terms of I/O operations per second (IOPS) for each virtual hard disk in their virtual machines. Storage QoS allows the administrator to ensure that storage throughput of one virtual hard disk does not impact the performance of another virtual hard disk on the same host. 

Storage QoS is not available for shared virtual hard disks.

Live Migration

Hyper-V live migration has been updated with improved performance and the ability to perform cross-version live migrations.

Performance options which are now available include: 

  • TCP/IP - The memory of the virtual machine is copied to the destination server over a TCP/IP connection. This is the method which was used in Hyper-V in Windows Server 2012.
  • Compression - The memory content of the virtual machine which is being migrated is compressed and then copied to the destination server over a TCP/IP connection. This is the default setting in Hyper-V in Windows Server 2012 R2. 
  • SMB 3.0 protocol - The memory content of the virtual machine is copied to the destination server over a SMB 3.0 connection. This means SMB Direct and SMB Multichannel can be made use of to increase performance if they have been configured on the servers. 

Cross-version live migrations allow virtual machines to be migrated from Windows Server 2012 and Windows Server 2012 R2. This allows upgrading to a new version of Windows Server on Hyper-V hosts without a downtime on virtual machines.

Virtual Machine Generations

Hyper-V in Windows Server 2012 R2 includes support for a second virtual machine generation. 

Generation 1 virtual machines provide the same virtual hardware to the virtual machine as in previous versions of Hyper-V

Generation 2 virtual machines provide the following new functionality: 

  • Secure Boot (enabled by default)
  • Boot from a SCSI attached virtual hard disk
  • Boot from a SCSI attached virtual DVD
  • PXE boot by using a standard network adapter (previously required a legacy network adapter) 
  • UEFI firmware support

Generation 2 virtual machines support a limited number of guest operating systems including: 

  • Windows Server 2012
  • Windows Server 2012 R2
  • 64-bit versions of Windows 8
  • 64-bit versions of Windows 8.1

Integration Services

Integration Services have been updated to allow Hyper-V administrators to copy file to a virtual machine while the virtual machine is running without using a network connection.


Hyper-V now supports exporting a virtual machine or virtual machine checkpoint while the virtual machine is running. It is no longer necessary to shut down a virtual machine before an export operation. 

Failover Clustering and Hyper-V

Hyper-V is now able to detect physical storage failures on storage devices not managed by Windows Failover Clustering such as SMB 3.0 file shares. Storage failure detection can detect the failure of a virtual machine boot disk or data disk associated with a virtual machine and Windows Failover Clustering will ensure that the virtual machine is relocated and restarted on another node in the cluster.  

Enhanced Session Mode

Virtual Machine Connection in Hyper-V allows redirectoin of local resources in a Virtual Machine Connection session. 

This feature enhances the interactive session for Hyper-V administrators connecting to their virtual machines. It provides similar functionality to a remote desktop connection to the virtual machine but does not require a network path to the virtual machine. 

The follow local resources can be redirect when using Virtual Machine Connection: 

  • Display configuration
  • Audio
  • Printers
  • Clipboard
  • Smart cards
  • Drives
  • USB devices
  • Supported Plug and Play devices

Only Windows Server 2012 R2 and Windows 8.1 support enhanced session mode connections. 

Hyper-V Replica

Hyper-V Replica adds two new features to Hyper-V. 

You can configure extended replication. With extended replication the replica server forwards information about changes in the primary virtual machine to a third server (the extended replica server). After a failover from the primary server to the replica server the extended replica server provides an additional level of business continuity protection. 

The frequency of replication is now configurable and an administrator is now able to access recovery points for 24 hours. Previous versions allowed access to recovery points for 15 hours. 

Linux Support

Linux virtual machines can now be backed up in the same manner as virtual machines running Windows. Supported Linux operating systems with updated integration services components appear in the list of available virtual machines when backing up a server running Hyper-V. 

Dynamic Memory support is now available for Linux guest operating systems. Any supported Linux operating systems with updated integration services components are now able to take advantage of Dynamic Memory the same way virtual machines running Windows are. 


An administrator can manage Hyper-V in Windows Server 2012 from a computer running Windows Server 2012 R2. In previous releases it was not possible to connect to and manage down-level versions of Hyper-V. 

Automatic Virtual Machine Activation

This feature allows an administrator to install virtual machines on a computer Windows Server 2012 R2 is properly activated without having to manage product keys for each individual virtual machine. Automatic Virtual Machine Activation (AVMA) binds the virtual machine activation to the licensed virtualization server and activates the virtual machine when it starts. AVMA also provides real-time reporting on usage as well as historical data on the license state of virtual machines.

SCVMM 2012 R2


Site-to-site network connections using private IP addresses: 

  • Support for setting guest IP address configuration through VMM as well as support for dynamic IP addresses to enable guest clusters.
  • Site-to-site NVGRE gateway support. This enables virtualized network hosters to achieve higher capacity and better reliability. It also offers options for the tenants on the networks using all Microsoft software. 
  • Cisco NVGRE (network virtualization using generic routing encapsulation) allows the VMM provider API to be more flexible to address a variety of network services as well as simplify the user experience. Network services such as load balancers, for example, are able to function as network virtualization gateways. Additionally, switch extensions have access to network virtualization policy to determine the owner of packets being sent.
  • IP Address Management (IPAM) integration
  • Top of rack switch integration
  • Forwarding extensions for Hyper-V extensible switch work with Hyper-V network virtualization (Cisco 1KV and NVGRE) 

Virtual Machines and Cloud

Optimized support for differencing disks to improve performance of virtual machine provisioning. They also reduce storage capacity requirements by allowing a large percentage of disk data to be shared among multiple virtual hard disks.

Live cloning of virtual machines allows for cloning of virtual machines without downtime. 

Online VHDX resizing is included in SCVMM 2012 R2 to support the new Hyper-V VHDX resizing feature. 

Dynamic memory support has been enhanced to allow settings to be applied to a running or paused virtual machine. 

Administrators can now customize the scope of permitted activities users are allowed to perform on a per cloud basis. 

Support for file-based virtual machine customization allows the injection of a file into a specified path in the virtual machine drive or file path prior to the first boot. 

The ability to leverage the new Hyper-V file transfer API in Windows Server 2012 R2 which allows the transfer of files from the host to a guest even when the virtual machine does not have a connection to a network with access to the VMM library server. 

The ability to create Windows and Linux based virtual machines and multi-VM services from templates has been added. 

Faster live migration and support for live migration of Windows Server 2012 R2 host operating systems has been added.


Support for management and automated provisioning of fibre channel fabrics for virtual machines has been added. 

Management of zones has been added.

Enhanced support for Offloaded Data Transfer (ODX) for high availability scenarios is included. 

SCVMM 2012 R2 has support for shared VHDX for guest clustering.

The ability to provision scale-out file server clusters from bare metal is available in SCVMM 2012 R2. 

Integration and management of storage spaces offers greater ability to manage the storage infrastructure used in the virtualization environment. 


Support has been added to allow for deploying VMM in System Center 2012 SP1 services to XenServer Hosts. 

The ability to allow the script that runs on a the first deployed virtual machine to be different than the script that runs on other virtual machines in that tier is included. 


It is now possible for an auto-task resume to occur after a virtual machine failover.

There is an expanded computer scope for VMM update management. 

Management packs have been updated with new metrics which are based on allocation and utilization. 

Other Enhancements

Support for Windows Server 2012 R2 and Windows 8.1 in various roles such as VMM management server, VMM library server and Hyper-V host have been added. 

Enhancements to replication and recovery have been added. 

Direct links to missing prerequisites have been added to the setup wizard. 


It is clear there have been many significant enhancements to Microsoft's Private Cloud offering with the updates included in Windows Server 2012 R2 and System Center 2012 R2 Virtual Machine Manager. The increasing number of features in the latest software versions from Microsoft continue to position their solution as a top choice for deploying a private cloud. 

KB2836402 - You cannot add VHD files to Hyper-V virtual machines in Windows Server 2012

Microsoft has posted a knowledge base article about a scenario where VHD or VHDX files cannot be added to Hyper-V virtual machines in Windows Server 2012.


Consider the following scenario:

  • You create some failover cluster nodes on computers that are running Windows Server 2012.
  • You have the Hyper-V server role installed on the cluster nodes.
  • You create virtual machines on one cluster node, and you configure the virtual machines as cluster resources.
  • You create multiple Cluster Shared Volume (CSV) resources and create one Virtual Hard Disk (VHD) file in each CSV.
  • You use Hyper-V Manager to try to add the VHD files to the virtual machines.

In this scenario, you cannot add the VHD files to the virtual machines. Additionally, you receive an error message that resembles the following:

Error applying Hard Drive changes 
‘Virtual machine‘ failed to add resources to ‘virtual machine‘ 
Cannot add ‘C:\ClusterStorage\Volume3\Test3.vhdx‘. The disk is already connected to the virtual machine ‘virtual machine‘. (Virtual machine ID virtual machine ID) 
‘Virtual machine‘ failed to add resources. (Virtual machine ID virtual machine ID) 
Cannot add ‘C:\ClusterStorage\Volume3\Test3.vhdx‘. The disk is already connected to the virtual machine ‘virtual machine‘. (Virtual machine ID virtual machine ID)


This issue occurs because multiple CSV volumes have the same 0000-0000 serial number. Therefore, the VHD files on different volumes are recognized as the same file.

There is a supported hotfix available from Microsoft.

KB2838669 - Update that improves cluster resiliency in Windows Server 2012 is available

There was a big Failover Clustering update today which solves several issues.

Issue 1
Consider the following scenario:

  • You have the Hyper-V server role installed on a Windows Server 2012-based file server.
  • You have lots of virtual machines on a Server Message Block (SMB) share.
  • Virtual hard disks are attached to an iSCSI controller.

In this scenario, you cannot access to the iSCSI controller. 

Issue 2
Consider the following scenario:

  • You have a two-node failover cluster that is running Windows Server 2012.
  • The cluster is partitioned.
  • There is a Cluster Shared Volume (CSV) on a cluster node, and a quorum resource on the other cluster node.

In this scenario, the cluster becomes unavailable.

Note This issue can be temporarily resolved by restarting the cluster.

Issue 3
Assume that you set up an SMB connection between two Windows Server 2012-based computers. The hardware on the computers do not support Offloaded Data Transfer (ODX). In this situation, the SMB session is closed unexpectedly.

Issue 4
Consider the following scenario:

  • You have a Windows Server 2012-based failover cluster.
  • You have a virtual machine on a CSV volume on the cluster.
  • You try to create a snapshot for the virtual machine. However, the snapshot creation is detected as stuck. Therefore, the snapshot set is aborted.
  • During the abortion process of the snapshot, the CSV volume is deleted after the snapshot shares are deleted.

In this scenario, the abortion process is paused automatically because of an error that occurs on the cluster.

Issue 5
Assume that you have a Windows Server 2012-based failover cluster. Two specific snapshot state change requests are sent from disk control manager to CSV proxy file system (CSVFS). The requests are present in the same message. In this situation, disk control manager is out-of-sync with CSVFS.

Issue 6
Assume that you create a snapshot for a CSV volume on a Windows Server 2012-based failover cluster. When the snapshot creation is still in progress, another snapshot creation is requested on the same CSV volume. In this situation, the snapshot creation fails and all later snapshot creation attempts on the CSV volume fail.

Note You cannot create a snapshot for the CSV volume until the volume fails over or the volume goes offline and then back online.

Additionally, the update also resolves the issues that are described in the following Microsoft Knowledge Base (KB) articles:

2799728 Virtual machine enters a paused state or a CSV volume goes offline when you try to create a backup of the virtual machine on a Windows Server 2012-based failover cluster

2801054 VSS_E_SNAPSHOT_SET_IN_PROGRESS error when you try to back up a virtual machine in Windows Server 2012

2796995 Offloaded Data Transfers fail on a computer that is running Windows 8 or Windows Server 2012

2813630 Virtual machine enters a paused state or a CSV volume goes offline when you try to create a backup of the virtual machine on a Windows Server 2012-based failover cluster

2824600 Virtual machine enters a paused state or goes offline when you try to create a backup of the virtual machine on a CSV volume in Windows Server 2012

There is a hotfix available.

KB2836988 - Windows 8 and Windows Server 2012 update rollup: May 2013

Microsoft has released another Update Rollup of hotfixes and a couple of the hotfixes are relevant to Hyper-V.

KB2836121 - An update for Storage Spaces in Windows 8 and Windows Server 2012 is available.

This article describes an update for Storage Spaces in Windows 8 and Windows Server 2012. After you install the update, Storage Spaces will prioritize regeneration. Specifically, the regeneration time is shorter, but the available bandwidth for the regular I/O buffer is decreased.

KB2833586 - Virtual machine does not come online after you add a pass-through disk to the virtual machine in Windows Server 2012.


Consider the following scenario:

  • You have a Windows Server 2012-based failover cluster. 
  • A Hyper-V server role is installed on the cluster node.
  • You create a virtual machine on the cluster node, and then you configure the virtual machine as a cluster resource.
  • You add a pass-through disk to the virtual machine by using Windows Management Instrumentation (WMI).

In this scenario, the virtual machine does not come online.

Note If you add the pass-through disk by using the Failover Cluster Management snap-in, the virtual machine does come online.