There are various reasons why it may be necessary to convert physical systems directly into virtual machines (VMs). Aging, out-of-warranty or failing hardware may necessitate such a migration, as may the simple need to consolidate underutilized systems to reduce operating costs. It is certainly possible to manually build guest VMs and migrate the applications and resources from the physical systems over to them, but this can be a time-consuming and error-prone operation. A simpler alternative is to perform a physical to virtual (P2V) migration to get these servers into a virtualized server environment. Here we’ll discuss Hyper-V P2V conversion, as well as the storage considerations around such a conversion.
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In a Hyper-V environment, in addition to the manual process, there are two methods of migrating physical servers to virtual servers that are considerably less error-prone than manual methods. These are to use Microsoft System Center Virtual Machine Manager (SCVMM) 2008 R2 SP1 and, somewhat surprisingly, using VMware vCenter Converter Standalone and Vmdk2Vhd (VMDK to VHD) tools. Of these two, SCVMM provides the more seamless and complete migration experience.
No matter which method you choose to create the VMs, in order to avoid migration difficulties, it is recommended that before moving VMs to a Hyper-V server, the appropriate hardware such as NICs, RAID controllers, Fibre Channel HBAs, etc., be installed in the Hyper-V server. In addition, pre-configuring external resources such as Ethernet switches, zoning in Fibre Channel switches, storage LUN masking, etc., should be performed before attempting to boot the newly created VM. In addition, simple things such as planning domain names and computer names should be done in advance. You should determine if you can or should run both the original physical server and the newly created VMs in parallel for a period of time, or if you will cut over to the VM only.
Storage for guest virtual machines
In our conversions to guest virtual machines in Hyper-V, we generally prefer to use the “pass-through” mode for the application server storage devices. This allows the application direct access to the storage device or devices in a manner similar to the way things work in the physical server environments. This process is the same for iSCSI or Fibre Channel storage. For iSCSI storage, the NIC in the Hyper-V server needs access to the same VLAN as the NIC in the original physical server.
Another option for iSCSI is to use the iSCSI direct method, which involves allocating the LUN directly from the iSCSI initiator. This method bypasses the hypervisor but requires that the iSCSI NIC (or offload card) be visible to the guest VM.
For Fibre Channel storage, the HBA of the Hyper-V server needs to be included in the appropriate Fibre Channel zone on the switch. In both cases, the LUN masking in the storage arrays needs to be adjusted to provide access to the new guest virtual machine.
Microsoft System Center Virtual Machine Manager 2008 R2 SP1
Microsoft offers SCVMM as a management utility to facilitate managing VMs in Hyper-V. It can be ordered from Microsoft or downloaded for evaluation. SCVMM offers what is probably the simplest and cleanest method of P2V conversion.
SCVMM must be installed on a domain-managed Windows Server 2008 R2 system. It will not install on a workgroup server and is a bit finicky regarding host name convention. For example, the server on which SCVMM is running cannot have hyphens in its computer name. The tool needs to be installed on a system (or systems, if spreading the server, database and administration console across multiple servers) with network access to the appropriate Hyper-V server and source physical systems.
Using SCVMM to perform Hyper-V P2V conversion is very intuitive and straightforward. Using the SCVMM console, a wizard is used to identify the Hyper-V host that will receive the virtual machines and the virtual machine path where the guest virtual machines will be stored. After the Hyper-V host has been added to the SCVMM console, the Hyper-V P2V wizard can be started to begin the process of moving the physical server into a VM on the Hyper-V host. The P2V conversion wizard steps through the process of selecting the desired resources that will be migrated to the virtual machine.
SCVMM will rate the appropriate Hyper-V servers according to their capability to support the resources required by the physical servers. When SCVMM has completed the task of building and configuring the VM, it can be started in the Hyper-V environment.
VMware vCenter Converter Standalone client
Although obviously intended for the conversion of physical systems to VMware virtual machines, VMware offers utilities that can be implemented to perform conversion to Hyper-V as well. While not providing quite as seamless of a conversion, the VMware tools have the advantage of being available for free download from VMware, as of this writing. Both the VMware vCenter Converter Standalone client and the Vmdk2Vhd tools need to be downloaded. These tools can be installed on any server or desktop machine that has network connectivity to the source physical server.
Because this tool is designed for conversions to a VMware environment and not directly for a Hyper-V environment, a VMware virtual machine must be selected as the destination. The output, a VMware VMDK file, will be created and then converted to a Hyper-V virtual hard disk (VHD) using the Vmdk2Vhd tool in a later step. As with SCVMM, some or all of the resources from the original physical server can be selected to be migrated to the new VM. After the VM is created in the VMDK format, then converted to a VHD, the new VM can be built in Hyper-V using the normal steps in Hyper-V.
Once the VM is built, it can be started in Hyper-V. The VM may need a reboot to reconcile hardware differences between the Hyper-V server and the original physical server. This is normal and expected.
Now some post-conversion work may be in order. Since the VMware vCenter Converter Standalone client does not perform the target Hyper-V server evaluation that SCVMM does, it is quite possible that more complex source system configurations will demand some additional configuration steps.
BIO: Dennis Martin is president at Demartek LLC, an Arvada, Colo.-based industry analyst firm that operates an on-site test lab.