1. Simonas Vaicekauskas IT3 grupė
Virtual Hard Disc
Simonas Vaicekauskas IT3 grupė

2. Turinys Kas yra Virtual Hard Disk(VHD) ? Kam reikalingas VHD?
Kaip veikia?
VHD ypatybės ir tipai

3. Kas yra Virtual Hard Disc
Failo formatas kuris yra matomas kaip HDD įrenginys
Palaiko standartines HDD operacijas
Pirma kart panaudota Microsoft virtual pc

4. Kaip veikia?
Virtualios mašinos OS mato kaip fizinį įrenginį

5. Ypatybės
User Mode Native Windows APIs: VirtDisk.dll - Common library for VHD management APIs.
User Mode Domain-specific Management Wrappers: VDS VHD APIs - VDS Object Model wrappers for the VHD Windows APIs.
Kernel Mode Drivers: VDrvRoot.sys - Root virtual drive enumerator.
FsDepends.sys - Nested volume dependency management.
Vhdmp.sys - VHD parser and dependency property provider.

6. Tipai Fixed – Išskirtas VHD failas su maximaliu vietos kiekiu.
Expandable arba dinaminis – Naudoja tiek vietos kiek reikia. Įmanoma sukurti su daugiau laisvos vietos negu fiziniame įrenginyje
Differencing

7. Privalumai ir Trūkumai
Lengva perkelti iš vienos virtualios mašinos į kitą
Lengva duplikuoti
Galimi tik 2TB vietos

8. GET_VIRTUAL_DISK_INFO_UNSPECIFIED Reserved
GET_VIRTUAL_DISK_INFO_UNSPECIFIED Reserved. This value should not be used.
GET_VIRTUAL_DISK_INFO_SIZE Information related to the virtual disk size, including total size, physical allocation used, block size, and sector size.
GET_VIRTUAL_DISK_INFO_IDENTIFIER The unique identifier. This identifier is persistently stored in the virtual disk and will not change even if the virtual disk file is copied to another file.
GET_VIRTUAL_DISK_INFO_PARENT_LOCATION The paths to parent virtual disks. Valid only for differencing virtual disks.
GET_VIRTUAL_DISK_INFO_PARENT_IDENTIFIER The unique identifier of the parent virtual disk. Valid only for differencing virtual disks.
GET_VIRTUAL_DISK_INFO_PARENT_TIMESTAMP The time stamp of the parent when the child virtual disk was created. Valid only for differencing virtual disks.
GET_VIRTUAL_DISK_INFO_VIRTUAL_STORAGE_TYPE The device identifier and vendor identifier that identify the type of virtual disk.
GET_VIRTUAL_DISK_INFO_PROVIDER_SUBTYPE The type of virtual disk.
GET_VIRTUAL_DISK_INFO_IS_4K_ALIGNED Indicates whether the virtual disk is 4 KB aligned.
Windows 7 and Windows Server 2008 R2:  This value is not supported before Windows 8 and Windows Server 2012.
GET_VIRTUAL_DISK_INFO_PHYSICAL_DISK Details about the physical disk on which the virtual disk resides.
GET_VIRTUAL_DISK_INFO_VHD_PHYSICAL_SECTOR_SIZE The physical sector size of the virtual disk.
GET_VIRTUAL_DISK_INFO_SMALLEST_SAFE_VIRTUAL_SIZE The smallest safe minimum size of the virtual disk.
GET_VIRTUAL_DISK_INFO_FRAGMENTATION The fragmentation level of the virtual disk.
GET_VIRTUAL_DISK_INFO_IS_LOADED Whether the virtual disk is currently mounted and in use.
Windows 8 and Windows Server 2012:  This value is not supported before Windows 8.1 and Windows Server 2012 R2.
GET_VIRTUAL_DISK_INFO_VIRTUAL_DISK_ID The identifier that is uniquely created when a user first creates the virtual disk to attempt to uniquely identify that virtual disk.
GET_VIRTUAL_DISK_INFO_CHANGE_TRACKING_STATE The state of resilient change tracking (RCT) for the virtual disk.
Windows 8.1 and Windows Server 2012 R2:  This value is not supported before Windows 10 and Windows Server 2016 Technical Preview.

9. VirtualStorageType [in] A pointer to a VIRTUAL_STORAGE_TYPE structure that contains the desired disk type and vendor information.
Path [in] A pointer to a valid string that represents the path to the new virtual disk image file.
VirtualDiskAccessMask [in] The VIRTUAL_DISK_ACCESS_MASK value to use when opening the newly created virtual disk file. If the Version member of the Parameters parameter is set to CREATE_VIRTUAL_DISK_VERSION_2 then only the VIRTUAL_DISK_ACCESS_NONE (0) value may be specified.
SecurityDescriptor [in, optional] An optional pointer to a SECURITY_DESCRIPTOR to apply to the virtual disk image file. If this parameter is NULL, the parent directory's security descriptor will be used.
Flags [in] Creation flags, which must be a valid combination of the CREATE_VIRTUAL_DISK_FLAG enumeration.
ProviderSpecificFlags [in] Flags specific to the type of virtual disk being created. May be zero if none are required.
Parameters [in] A pointer to a valid CREATE_VIRTUAL_DISK_PARAMETERS structure that contains creation parameter data.
Overlapped [in, optional] An optional pointer to a valid OVERLAPPED structure if asynchronous operation is desired.
Handle [out] A pointer to the handle object that represents the newly created virtual disk.

10. Version1 This structure is used if the Version member is CREATE_VIRTUAL_DISK_VERSION_1 (1).
UniqueId Unique identifier to assign to the virtual disk object. If this member is set to zero, a unique identifier is created by the system.
MaximumSize The maximum virtual size, in bytes, of the virtual disk object. Must be a multiple of 512.
If a ParentPath is specified, this value must be zero.
If a SourcePath is specified, this value can be zero to specify the size of the source virtual disk to be used, otherwise the size specified must be greater than or equal to the size of the source disk.
BlockSizeInBytes Internal size of the virtual disk object blocks, in bytes. This must be set to one of the following values.
ParentPath Optional fully qualified path to a parent virtual disk object. Associates the new virtual disk with an existing virtual disk.
If this parameter is not NULL, SourcePath must be NULL.
SourcePath Optional fully qualified path to pre-populate the new virtual disk object with block data from an existing disk. This path may refer to a virtual disk or a physical disk.
If this parameter is not NULL, ParentPath must be NULL.

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