What is the difference between vhd and avhd

The release of Windows Server brought many new virtualization improvements, but one that caught the eye of many IT pros was the introduction of the VHDX file format. The VHDX format also provides protection against file corruption related to power failures by continuously keeping track of updates in the metadata, a feature not available with the VHD format. Larger block sizes for dynamic and differencing disks, as well as the ability to store custom metadata, also give the new format the edge in the VHD vs.

VHDX comparison. Hyper-V allows you to create 2 primary hard disk storage types, fixed or dynamic. Dynamic size drives are allocated with the minimum space needed and space is expanded as you write additional drive to the volume. There is performance loss on disk writes that require storage to be expanded. For example, if you create a dynamic volume with 10 GB and as you write data and use up the entire 10GB allocation then the volume needs to be expanded first then your data will be written to the volume.

Fixed drive sizes presets the size for your storage. Since the file is preallocated on the Hyper-V host there is no loss in performance due to the need for expansion of space. In tests performed by others, they have seen negligible difference in overhead with Dynamic VHDX volumes when they expand to accommodate additional data.

As always, make a backup and make sure you have enough time allocated for the conversion. The larger the volume, the longer the conversion will take. For example, after deleting an old snapshot for WinAgent, you can see that the snapshot merge is in progress:. If you look in the file system for the.

As described in previous blogs, you can use the Unitrends product to protect your Hyper-V VMs Once a Hyper-V server is registered to the system, you will see the list of VMs in the navigational tree.

If you select a VM and start a backup, it uses Microsoft VSS snapshot technology to programmatically create a VSS snapshot and then transmit the backup data to the appliance. Note that this type of snapshot is not generated by the user so does not show up in the Hyper-V Manager.

However, you can see that a backup of the VM is in progress from the Hyper-V manager. As with Hyper-V snapshots the VM continues to run while being backed up. VSS Snapshots are disk only, and do not include in-memory state, and are intended for backup.

VSS manages its snapshots closely so as not to allow an aging snapshot to consume too much disk space, but Hyper-V snapshots can easily cause problems as they age.

Unitrends increases uptime, productivity and confidence in a world in which IT professionals must do more with less. Unitrends leverages high-availability hardware and software engineering, cloud economics, enterprise power with consumer-grade design, and customer-obsessed support to natively provide all-in-one enterprise backup and continuity. Hyper-V snapshots are primarily used to revert a VM to its previous state in case any unnecessary changes were applied to the VM and the user wants to discard them.

The main advantage of this technology is that Hyper-V snapshots can be easily and rapidly taken online and offline, without causing any workflow interruptions within a running VM.

In Hyper-V, multiple snapshots can be created, deleted, and applied to a single VM. Below, we list the top 10 facts about Hyper-V snapshots that every Hyper-V user should be aware of to successfully utilize this technology in their virtual environments. Some of you may wonder why we refer to the snapshot technology in Hyper-V as snapshots and not as checkpoints.

This can be seen as an attempt of Microsoft to create uniform Hyper-V terminology, which would be distinct from its main competitors. Both of these terms Hyper-V snapshots and Hyper-V checkpoints are equally valid; therefore, we will use both of them in this blog post. AVHD X files are stored in the same location as the original virtual hard disk. After the snapshot is created, all the changes in data are tracked and saved in the corresponding differencing disk AVHD X file until the new Hyper-V snapshot is created or this one is deleted.

At the same time, the original VHD file operates in a read-only mode. Prior to the release of Windows Server and Windows 10, only one snapshot type existed — Standard.

This type of snapshots can capture the VM state at a particular point time, including its memory. However, standard snapshots proved not to be sufficiently effective when applied in production environments. Due to this, Hyper-V production snapshots were introduced. The main advantage of production snapshots is that they apply Volume Shadow Copy Service for Windows or File System Freeze for Linux to create data-consistent and application-aware snapshots of the VM.

Thus, Hyper-V production snapshots have proven themselves to be extremely helpful in production environments. Hyper-V snapshots are generally created before installing new software, adopting configuration changes, performing operating system OS updates, or making registry changes.

Software updates and configuration changes may fail and lead to some undesirable results. Thus, it is a feasible option to create VM snapshots beforehand and use them in order to discard the adopted changes and roll back the VM to its previous state. It is clear that Hyper-V snapshots allow you to easily and rapidly revert the VM to its previous state before any damaging changes are applied.

Due to this, they can be considered a feasible tool for test and development environments.