Last week, we posted an introduction to VMware cloud migration, focusing on preparation and initial considerations like training and measuring current server usage. Today, we’ll start a closer examination of the migration process itself, using the integrated vCenter Conversion tool.
These steps can be used to migrate infrastructure to any VMware environment, whether you are setting up virtualization in-house or partnering with a cloud provider for a remote private or public cloud.
The method we will be examining is the free vCenter Converter tool from VMware, widely compatible with existing physical machines, VMs, and third-party images. It can convert Linux and Windows-based systems alike.
Alternatively, if your existing infrastructure is already running VMware, you can simply add your new public or external private cloud to vSphere using the vCloud Connector. This can be accessed via the vSphere client or online at vmware.com.
VMs can easily be copied, moved between environments, and operated on with the vCenter Converter. Note: the vCenter Converter will not recognize volumes or file systems on disks that are 2TB or greater in size. The following formats are accepted:
|Importable VM Formats||Importable 3rd Party Images||Created VM Formats|
VMware vCenter Server
Microsoft Virtual PC
Microsoft Virtual Server
Symantec Backup Exec
Acronis True Image
The next decision to make is whether you will perform a cold or hot migration (AKA cold or hot cloning). Cold cloning involves powering down your machine, inserting a disc with an operating system and vCenter installed, and copying the entire powered down system. It creates a more exact copy of the machine state.
Hot cloning copies a machine as it is running, meaning some active processes may not be copied, but can be performed without any downtime. The Converter Standalone can also shut down relevant Windows processes based on user settings to avoid critical changes in the resulting VM. Converter Standalone can turn off the physical machine after conversion and power on the VM immediately for seamless migration.
The following example is a hot conversion of a Windows machine with no downtime. Install vCenter Converter and follow the wizard to set up conversion tasks. The Standalone agent takes a snapshot of the source volumes, creates a virtual machine on the destination server and then copies volumes across the network. It will automatically install required drivers so the operating system can boot on the virtual machine and personalizes some information like IP addresses. If set to do so, the agent will uninstall itself at the end of conversion.
When converting a Linux machine the process is slightly different. No agent is installed on the source machine, rather a VM is created on the destination host. This helper VM copies volumes using SSH and boots from an .iso file located on the Converter Standalone machine. After copying is complete the helper VM converts to a bootable VM containing the duplicated information.
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To convert an existing VM (VMware or Hyper-V based) or a third-party backup image, simply select it as the source volume in the conversion wizard. You will need to be connected to the relevant VM server. For running VMs you should use the procedure for hot cloning physical machines. Otherwise power down your VMware or Hyper-V VM before conversion.
Cloning can be volume, disk or link-based. Volume based cloning allows the user to select individual files or blocks. Dynamic disks are converted to basic volumes in this relatively slow type of cloning. Disk based cloning copies everything from the source machine, resulting in partitions of the same type, size and structure. Linked clones copy all data except sharable software data in order to save disk space. These clones require source access. You can also resize volumes before conversion to save disk space.
Network settings and hardware settings, from number of adapters to memory allocation, can be changed prior to conversion from Options. The Post conversion tab under Options allows the destination operating system to be customized as well, with identity, licensing and more.
Depending on your destination server, you can change the disk type. VMware Infrastructure virtual machines can be Thick or Thin, either copying the entire source disk or an expanding disk. Expanding disks copy only the used data with a provision to expand to the total available space on the source disk. On other instances, you can select pre-allocated, non pre-allocated, 2GB split pre-allocated or 2GB split non pre-allocated. Pre-allocated or not means essentially the same as Thick or Thin disks, where non pre-allocated disks are expandable. 2GB split options split the source disk into 2GB sections, which is required for FAT file systems.
After powering on your newly cloned VM, there are just a few more things to check. Namely, if your new VM exists on the same network as your old machine and you intend to use both of them, you must reconfigure network settings, name, SID, etc as they will have been copied intact. Applications that depend on specific hardware traits like serial numbers or MAC address will also need adjustment.
Posted By: Joe Kozlowicz