2.12.1 Ghosted Extents Stream Structure
A ghosted extent stream structure represents ghosted extents in the DATA backup stream. Ghosted extents are a kind of sparse extents, which store a GUID representing the owner of the extent and some variable-sized metadata. The structure of the data portion of this backup stream for a specific implementation is as follows:
|
|
|
|
|
|
|
|
|
|
1 |
|
|
|
|
|
|
|
|
|
2 |
|
|
|
|
|
|
|
|
|
3 |
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Count |
|||||||||||||||||||||||||||||||
|
TotalCount |
|||||||||||||||||||||||||||||||
|
Data (variable) |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
Count (4 bytes): The number of extents in the Data portion.
TotalCount (4 bytes): The total number of ghosted extents in the stream.
Data (Variable): The data portion of the above structure contains a variable number of extents. The number of extents is given by Count. The structure of each Extent is described below:
|
|
|
|
|
|
|
|
|
|
1 |
|
|
|
|
|
|
|
|
|
2 |
|
|
|
|
|
|
|
|
|
3 |
|
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
Offset |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
|
Length |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
|
Guid |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
|
NextOffset |
|||||||||||||||||||||||||||||||
|
Size |
|||||||||||||||||||||||||||||||
|
Data (variable) |
|||||||||||||||||||||||||||||||
|
... |
|||||||||||||||||||||||||||||||
Offset (8 bytes): The logical byte offset in the DATA backup stream where the ghosted extent starts.
Length (8 bytes): The logical length of the ghosted extent.
GUID (16 bytes): The GUID identifier of the owner for the ghosted extent.
NextOffset (4 bytes): Offset to the next Extent structure.
Size (4 bytes): Size of the metadata of the ghosted extent.
Data (variable): Metadata of the ghosted extent.