Learn Hyper-V Part 2

I am adding the specific features of Hyper-V that have been utilized by me and my team  and i have tried to learn more of them.

CPU Resource Allocation

Hyper-V is able to allocate host server physical CPU resources among running virtual machines with a flexible CPU Resource Allocation model. Hyper-V supports both weight-based and constraint-based CPU resource allocation for balanced workload management. The number of virtual machines that can be hosted on any server depends on the:

  • · Combined processor, memory, and I/O load the virtual machines put on the host
  • · Processor, memory, and I/O capacity available on the host system.

To explain, all virtual machines share CPU. when there are multiple users, once can share the RAM equally  every user. when there are no users during late night testing, one can allocate more RAM(up to 100%) to a virtual machine and speed up the job. My test engineer is happier as he perform the same job faster. Additional  settings available for handing CPU allocation includes

  • The minimum capacity and maximum capacity  of a single CPU that is reserved for specific virtual machine.
  • The percentage of total system CPU capacity that is reserved for this virtual machine.
  • The relative weight given to the resource needs of this virtual machine compared to all other virtual machines.This indicate how to allocate resources during contention

Virtual Machine Security

Hyper-V enables fine-grained administrative control over virtual machines with per-virtual machine ACLs that can be managed from within Active Directory’s Group Policy Management Console. For example, VM administrators don’t have to be administrators of the parent partition. This functionality appears to bring delegated access with Hyper-V on par with VirtualCenter with regards to role-based access. As user of Hyper-V image or Hyper-V server, we need to be aware of 

  • Each operating system running on a virtual machine needs its own firewall, antivirus, and intrusion detection software as appropriate for the environment.
  • File system security needs to configured to prevent unauthorized access to critical virtual machine resources, such as VHD files. Object access auditing can help detect potentially harmful activity by users. Be aware that users of virtual machines shall not be provided with access to the host operating system.
  • if a virtual machine is offline it cannot automatically receive updates through mechanisms such as Windows Update . If deployed and started, the out-of-date virtual machine might be vulnerable to attack. Microsoft provides a free tool for download The Offline Virtual Machine Servicing Tool 2.0.1, to automate the process of updating offline virtual machines.

Virtual Machine Snapshots

Hyper-V is integrated with the Microsoft Volume Shadow Copy service to enable administrators to create point-in-time snapshots of running virtual machines and create backup of running virtual machines.  Point-in-time snapshots enable

  • developers and testers to roll back VM system configurations to "last known good" status. Some kinds of development and testing involve a lot of waiting for programs and operating systems to install, uninstall, and reinstall. With the Snapshot feature of Hyper-V, a VM can be reset to a previous configuration, minimizing the need to uninstall programs or reinstall operating systems.
  • Administrators to implement complex or high risk configuration changes, and have the option to roll back to "last known good" status. Developers and testers to create and destroy VMs from a configuration library instead of requiring administrator help.

This results in storage efficiency, saves machine costs and reduce the administrator overhead.  In my current project, we migrated our test environment to Hyper-V server and reduced the number of test machines from 6 to 1.   

When the administrator creates snapshot of a virtual machine, Hyper-V ensures that the virtual machine is in a consistent state before the snapshot is taken . Effectively system backups of virtual servers can happen without downtime for the virtual server. This provides greater backup scheduling flexibility for administrators.

Hyper-V on Server Core

Server Core installations of Windows Server 2008 can be used to host core infrastructure roles in Hyper-V virtual machines. Server Core has a significantly smaller memory footprint and is the lowest-overhead platform for running Hyper-V.

Would learn and try to summarize my learning on Server Core in a separate blog. My test engineers warn that sever core has no user interface and you need to work like UNIX at the command prompt.

Support for non-windows machines

Hyper-V supports 64-bit and 32-bit VMs running Windows, Linux, , as well as 32-bit VMs compatible with most major operating systems. For example, a Linux-based vertical application tied to a manufacturing process should be able to coexist with Windows-based applications in other areas.