Benefits and Features

With VHD End Users Can:

• Get Up-And-Running Fast

User experience of the PC use is identical to conventional implementation and may be unaware that their computer does not have a physical hard disk and instead are being streamed a virtual hard disk across the network.

• Lower Maintenance Requirements

Upgrades and patches to OS image are deployed automatically and available on client reboot. This significantly reduces the time-consuming hands on software maintenance visits for, perhaps thousands of, computers in middle or large scale enterprise, and therefore drastically reducing maintenance costs.

• Increase Productivity

In a computers system the most vulnerable components to malfunction are client hard disks. In the circumstances of damaged hard disks the solution means not only the cost and time of replacing the hard disk but also the data lost. In a virtual hard disk system these problems are eliminated as the information is store on the server along with backup and restore features in order to minimize such problems.

• Login Anywhere, Anytime

All PCs become identical, so full consistency is ensured. This allows the users to login using any computers and be delivered their own personal virtual hard disks.

• Run Multimedia Apps, Use Peripherals

A virtual hard disk solution uses distributed computer so that the computer makes full use of it's local processing power, device drives and peripheral devices. This means that computers can have the full functionality and speeds as they would expect from a legacy implementation in order to run multimedia applications and access peripheral devices.

With VHD IT Administration Can:

• Rapidly Deploy Images

Use a single image to stream to many clients computers. This means that any installations or updates need only be applied once.

• Simplify Management

Easy and flexible management of a centralized system compared to a traditional computer model can greatly reduce management costs.

• Eliminate Hands-On Visits To Client PCs

All software issues solved server-side or with a simple client reboot, solving a significant management burden.

• Backup & Secure Client Data

Using built-in snapshot tools functionality to enhance the security of user data and control user access centrally to prevent malicious or accidental loss of data.

• Ensure Authorized Access

Provides Operating System level authenticated system access. In other words, verification and authentication of the user takes places before they even have acces to an OS. The provides high confidence in the system security.

Rapid Deployment

VHD software can be rapidly deployed server side and client side eliminating traditional waiting times for installation and usage.




• Software and Hardware Isolation Methodology

If you try and move a physical hard disk containing a windows installation form one computer to another with different hardware– the windows boot will fail. This is because the initial installation of windows uses a specific hardware configuration. This problem is especially relevant in a diskless environment where several computers -- with different hardware – want to boot from a single disk image.

VHD introduces a new deployment methodology for this type of diskless setup. By treating a windows installation as two parts: one we will call the System/Data-related part (SDP) and the other the Hardware Configuration Part (HCP) we can isolate the latter part. VHD tools can isolate a HCP for a windows installation and store this configuration as a file to be stored on the server. VHD software uses the Disk Image + HCP to stream to a client computer. Different HCP parts can be installed into the same image, so that a single image can be streamed to computers with different hardware.

Isolation of a hardware configuration only needs to be done once for each group of computers that have the same hardware – meaning less setup time and quicker deployment. If additional computers are added in the future our tools can be used again to isolate a new HCP file.




• Instant Access

Adding a new computer (with the same hardware) to the system is as simple as assigning it the appropriate HCP from the server.


Unparalleled Scalability




System scalability is of vital importance to your organization when choosing a new IT architecture and that means both geographical and load scalability.

In legacy implementation of diskless streaming the server must be located on the same local network as the client desktops, due to the use of proprietary DCHP server software. The unique of VHD software allows you to boot across routers on a Wide Area Network. In other words client PCs on several LANS can connect to a single boot server. By being fully compatible with stand alone DCHP servers you can locate your streaming server at a remote location to your actual client PCs – even across the Internet!

• Geographic Scalability

Easily install new client PCs and expand either on the same network; or on an entirely different LAN.

• Load Scalability

Multi-server load-balancing means that the simple addition of more I/O servers can service any number of addition clients – no matter what their hardware type.

Only one boot server is ever required.


High Compatibility




A VHD unique software tool allows customers to isolate new hardware configurations for all their current and future computers.

• Hardware Compatibility

A great advantage of streamed diskless solutions is that all current and future peripherals will work – exactly if they would if there were a physical disk drive inside the client PC. VHD software works with all hardware configurations and all modern PCs and is compliant with MS Drive Test Manager (certificate pending).

• Server Requirements

The server requirements of VHD software is much lower than that of a Server-Client or Thin Client model – for example a Pentium IV with 2GB of RAM and 100GB HD could service 50 clients. The other requirements are a PCI/PCI-E Network Interface card and the computer to be running Microsoft Server 2003/2008.

• Client Requirements

The PC requirements are also low. Just PXE compatibility is required – and this is almost certain for all computers shipped since 1998. We recommend your PCs meet the requirements to run XP or VISTA.

• Software Compatibility

Integration with, and support for Microsoft Active Directory is a very important advantage of VHD software. This allows each client PC to have its own personality – but still be streamed from a single image.

VHD software virtualizes the centralized storage of the client hard disks. VHD software uses Microsoft’s virtual hard drive format .vhd which is a well defined and documented storage method – for your confidence and peace of mind. The client .vhd files can be opened, viewed and edited server-side using MS Virtual PC. Therefore .vhds can also be created there, duplicated and edited remotely – before deployment.

VHD software is compliant with PXE v2.1.


High Availability




VHD implements three disk pack types to stream the virtualized disks. A pack is container which may combine multiple virtual hard disks and works in a similar way to RAID.

• The Simple Pack

This is composed of only one virtual hard disk, dedicated to a single I/O server. An I/O server failure disables the system. This is the same as the Balanced Pack (see next) but with only a single I/O server.

• The Balanced Pack

This is composed of multiple virtual hard disks from different I/O servers, and all the virtual hard disks have identical content. Only one virtual hard disk is linked to at any one time – as determined at boot up. If one I/O server fails, a simple reboot will reconnect the client to the pack to an alternative active server.

• The Concurrent pack

The concurrent pack is composed of multiple hard disks from different I/O servers and all disks are linked to at the same time. If an I/O server failures then there is a seamless operational continuity using the alternative servers – without requiring a reboot.

• Planned Downtime

This is eliminated because update changes are administered on the server. Only once they are finished and tested are they deployed. They are deployed in the time it takes client PCs to reboot!

• Unplanned Downtime

Streaming diskless software reduced the Mean Time to Repair (MTTR) because a software-only solution eliminates all the numerous problems associated with client Hard Drive failure. Software problems can also be solved with a simple reboot of the client PC – and if a problem persists then the image can simply be rolled back to a previously working image.


Flexible Usability




• Dynamic Image Loading

On start-up the use can chose an image to load from their image-menu. Each menu lists several virtual disks that can include different OS-Application combinations – depending on customer requirements.

• Protected Disk Access

• Refreshed Disk Storage

Every reboot provides a “refreshed” image of the disk and so there is no persistent data storage on these disks. Perfect for use of a vhd containing the OS, e.g. the C: drive or a common Applications drive.

• Persistent Disk Storage

Data can be stored on these disks and retrieved on the next boot. This data can be backed up using our built-in tools or third-party software. This could be used for a D: drive for example, to store user's data.

• Snapshot Function

The “snapshot function” allows the current changes to the data to be saved using a differential system. The system can be “rolled back” to any previous snapshot.

• Shadow Function

This allows the admin to see any .vhd file snapshot and so snapshots can be viewed and monitored on the server, and if required, rolled-back.