Frequently Asked Questions for Win 7 Virtualized Hard Disks

1. What are the different types of VHD files?

VHD files are divided into three types, which can be used with Hyper-V Manager or Windows in Windows 7. The disk management tool creates these file types:

1. Fixed VHD. The virtual disk size to which a fixed VHD file is allocated is the virtual disk size specified when the VHD was created. For example, if you create a virtual hard disk that is 2 GB in size, the system creates a file that is approximately 2 GB in size, some of which is used for the internal VHD structure. The size of a fixed VHD does not change as data is written to the virtual hard disk.

2. expand or dynamic VHD. At any given time, the size of an extensible or dynamic VHD file is the same as the actual data size written to the file. As more data is written, the file is dynamically increased. For example, a file that supports a 2 GB virtual hard disk is initially about 2 MB in the host file system. As data is continuously written to this virtual hard disk, the file grows until it reaches the 2 GB capacity limit.

3. Difference VHD. The difference VHD is similar to a dynamic VHD, but only contains modified virtual disk blocks for the associated parent virtual disk. Differences VHDs are linked to a specific parent VHD, called a child VHD. The parent VHD file is read-only; all modifications are made to the child VHD. The VHD file type of the parent VHD can be any of these three VHD types, including another differential VHD. Multiple sub-VHD files can form a differential chain.

Second, why is it recommended to use fixed VHD files for production?

The reason for using fixed VHD files for production is as follows:

" Since there is no need to dynamically expand VHD File, so I/O performance is the highest of the three VHD disk types. Also, if you write to a fixed VHD file, the underlying host volume of the VHD file does not run out of available disk space because the dynamic VHD requires expansion. And failed.

" Dynamic and differential VHD files depend on multiple data write operations and internal block allocation information if all I/O operations on the host volume and VHD files on the physical disk are not completed and are not Saved on a physical disk, this information may become inconsistent. This can happen when the underlying disk is completely powered down or the system suddenly loses power.

When, when is it suitable for using dynamic or extended VHD files?

Dynamic VHD is very useful when using Windows images in the following non-production environments: lower storage requirements and data in VHD The reliability of the access is more advantageous than the convenience of replacing the VHD file. For example, a test environment can store many dynamic VHDs on a network share to save space, without the need to allocate a fixed VHD format to the storage space required for unused portions of the image. In general, the test environment can easily rebuild, rebuild the VHD image can also be used for testing. Copying smaller dynamic VHD files from a network share to a local disk is faster than transferring a fixed VHD file of the same maximum size. If you can regenerate the entire contents of a dynamic VHD from other sources and the critical data is stored in a volume other than the dynamic VHD, consider using a dynamic VHD in a production environment.

Fourth, when child differences What happens when the VHD's parent VHD changes?

Child differences VHD contains modified data blocks in a specific parent VHD. If the parent VHD is changed or replaced with another VHD file with the same file name, the block structure between the parent VHD and the child VHD will no longer match and the contents of the child VHD will also be destroyed.

V. differencing VHD parent if the child can be located on different volumes or remote shared?

For native VHD boot, child differencing VHD required to link the parent VHD file These two files are on the same volume. Even if the parent and child disks reside on the same local disk, they cannot reside on different volumes. When a VHD other than the native VHD boot (such as an image management operation) is attached, the parent of the differencing disk can be in another volume or even a remote share.

Six, "Create VHD" and "additional VHD" What are the features?

Disk Management tool (DiskPart command-line tool and the Disk Management console) support creating additional and separate operations. "Create VHD" creates a new .vhd file with the type and size specified by the option. .vhd newly created files can be viewed as similar to the original disk. The "additional VHD" operation requires the storage system to use the VHD as a disk attached to the system. After performing the "attach VHD" operation, you can use the Disk Management tool to create one or more disk partitions within the VHD and format the NTFS file system within the VHD. If the VHD already has a disk partition and a file system volume when performing an "additional VHD" operation, the system will assign a drive letter to the volume within the VHD and the volume will be available, which is inserted into the USB connector. The situation occurs when the USB disk drive is similar. "Additional VHD" is sometimes referred to as "display VHD", because the VHD file system is assigned a drive letter and displayed, and Kegongshiyong. (Perhaps the display VHD can be compared to the submarine surfaced and can be seen.)

After performing the "Additional VHD" operation, the system will assign a drive letter to all volumes in the VHD and make it global Visible in the namespace. Whether you can see the attached VHD volume is not limited to the current user context. All users can see the attached VHD just like viewing a physical disk. VHDs can only be attached by users who have volume management privileges (by default only to administrators) because attaching a disk is equivalent to bringing a disk or volume online.

VII. What file systems can VHD use?

If you already have a .vhd file, you can save the .vhd file in any FAT, ExFAT, NTFS, or UDFS volume. However, you can only attach a VHD that is located on an NTFS volume. Performing an additional operation on a VHD on a non-NTFS volume will fail.

When creating a VHD, you can create one or more partitions in the VHD and format them using FAT, ExFAT, or NTFS. Additional operations make one or more volumes in the VHD available.

8. Can Windows 7 attach a VHD located in a remote share?

Yes, you can attach a VHD file located on a remote SMB share, and the VHD file will appear as a local disk. Other remote file systems such as NFS or FTP are not supported. Drives are assigned to volumes contained in the VHD, and these volumes are accessible to all users on the local system, depending on the security permissions of the data in the VHD volume. Remote VHD add-on support for remote image management.

Nine, can I use NTFS compression or encryption for VHD files?

VHD files compressed with NTFS on the host volume will not be attached as virtual hard disks. VHD files encrypted with Encrypting File System (EFS) on the host volume are also not attached as virtual hard disks. VHD files compressed or encrypted on the host volume will not be available for VHD native boot. However, if additional support is provided, the volumes within the VHD can use compression and encryption.

10. Can I use BitLocker to encrypt the entire VHD?

VHD files can be saved on BitLocker-protected host volumes, but VHD files on BitLocker protected volumes cannot be used for local boot . Enabling BitLocker for volumes contained within a VHD is not a supported configuration.

11. What are nested VHDs and what are nesting restrictions?

VHD is a file on the host volume. For example, the VHD file c:\\vhd\\ExampleFixed.vhd represents a fixed VHD file located in the \\vhd directory on the c: volume. In ExampleFixed.vhd, you can create a partition, initialize the NTFS file system volume, and then temporarily assign the drive letter m:. You can also create a new VHD file under m:\\vhd\\AnestedFixed.vhd. The second vhd file is created on the file system volume in the first vhd file. This is the nested VHD. Performing an "attach VHD" operation on c:\\vhd\\ExampleFixed.vhd will make the m: volume available. Performing an "additional VHD" operation on m:\\vhd\\AnestedFixed.vhd will make another volume (such as "n:") available. You can only attach up to 2 levels of nested VHDs. This means that you can attach a VHD to another additional VHD. However, if you attach a VHD to another add-on VHD that is already another add-on VHD, it will fail.

12. Can I configure two additional VHDs as dynamic disks?

A dynamic disk is a disk that is initialized for dynamic storage and contains dynamic volumes such as simple volumes and spans. Volume, striped, mirrored, or RAID-5 volume. Additional VHDs cannot be configured as dynamic disks.