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VSS_FILE_SPEC_BACKUP_TYPE enumeration (vss.h)

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The VSS_FILE_SPEC_BACKUP_TYPE enumeration is used by writers to indicate their support of certain backup operations—such as incremental or differential backup—on the basis of file sets (a specified file or files).

File sets stored in the Writer Metadata Document are tagged with a bit mask (or bitwise OR) of VSS_FILE_SPEC_BACKUP_TYPE values indicating the following:

  • Whether the writer and the requester have to evaluate a given file set for participation in the specified type of backup operations
  • Whether backing up the specified file will require a shadow copy

Syntax

typedef enum _VSS_FILE_SPEC_BACKUP_TYPE {
  VSS_FSBT_FULL_BACKUP_REQUIRED = 0x1,
  VSS_FSBT_DIFFERENTIAL_BACKUP_REQUIRED = 0x2,
  VSS_FSBT_INCREMENTAL_BACKUP_REQUIRED = 0x4,
  VSS_FSBT_LOG_BACKUP_REQUIRED = 0x8,
  VSS_FSBT_FULL_SNAPSHOT_REQUIRED = 0x100,
  VSS_FSBT_DIFFERENTIAL_SNAPSHOT_REQUIRED = 0x200,
  VSS_FSBT_INCREMENTAL_SNAPSHOT_REQUIRED = 0x400,
  VSS_FSBT_LOG_SNAPSHOT_REQUIRED = 0x800,
  VSS_FSBT_CREATED_DURING_BACKUP = 0x10000,
  VSS_FSBT_ALL_BACKUP_REQUIRED = 0xf,
  VSS_FSBT_ALL_SNAPSHOT_REQUIRED = 0xf00
} VSS_FILE_SPEC_BACKUP_TYPE, *PVSS_FILE_SPEC_BACKUP_TYPE;

Constants

 
VSS_FSBT_FULL_BACKUP_REQUIRED
Value: 0x1
A file set tagged with this value must be involved in all types of backup operations.


A writer tags a file set with this value to indicate to the requester that it expects a copy of the current
version of the file set to be available following the restore of any backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_FULL.
VSS_FSBT_DIFFERENTIAL_BACKUP_REQUIRED
Value: 0x2
A writer tags a file set with this value to indicate to the requester that it expects a copy of the current
version of the file set to be available following the restore of any backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_DIFFERENTIAL.

This value is not supported for express writers.
VSS_FSBT_INCREMENTAL_BACKUP_REQUIRED
Value: 0x4
A writer tags a file set with this value to indicate to the requester that it expects a copy of the current
version of the file set to be available following the restore of any backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_INCREMENTAL.

This value is not supported for express writers.
VSS_FSBT_LOG_BACKUP_REQUIRED
Value: 0x8
A writer tags a file set with this value to indicate to the requester that it expects a copy of the current
version of the file set to be available following the restore of any backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_LOG.

This value is not supported for express writers.
VSS_FSBT_FULL_SNAPSHOT_REQUIRED
Value: 0x100
A file set tagged with this value must be backed up from a shadow copy of a volume (and never from the
original volume) when participating in a backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_FULL.
VSS_FSBT_DIFFERENTIAL_SNAPSHOT_REQUIRED
Value: 0x200
A file set tagged with this value must be backed up from a shadow copy of a volume (and never from the
original volume) when participating in a backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_DIFFERENTIAL.
VSS_FSBT_INCREMENTAL_SNAPSHOT_REQUIRED
Value: 0x400
A file set tagged with this value must be backed up from a shadow copy of a volume (and never from the
original volume) when participating in a backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_INCREMENTAL.
VSS_FSBT_LOG_SNAPSHOT_REQUIRED
Value: 0x800
A file set tagged with this value must be backed up from a shadow copy of a volume (and never from the
original volume) when participating in a backup operation with a
VSS_BACKUP_TYPE of
VSS_BT_LOG).
VSS_FSBT_CREATED_DURING_BACKUP
Value: 0x10000
A writer tags a file set with this value to indicate to the requester that they expect the file to be created during the snapshot sequence.
VSS_FSBT_ALL_BACKUP_REQUIRED
Value: 0xf
The default file backup specification type. A file set tagged with this value must always participate in
backup and restore operations.
VSS_FSBT_ALL_SNAPSHOT_REQUIRED
Value: 0xf00
The shadow copy requirement for backup. A file set tagged with this value must always be backed up from a
shadow copy of a volume (and never from the original volume) when participating in a backup operation.

Remarks

When a writer sets a backup-required value of the VSS_FILE_SPEC_BACKUP_TYPE enumeration, it is indicating that the requester perform the backup in such a way that, when the backup is restored, the current version of the file set is restored. Typically, this means that the file set is copied as part of the backup.

This setting can be overridden if a file is added to the Backup Components Document as a differenced file (using IVssComponent::AddDifferencedFilesByLastModifyTime) or as a partial file (using IVssComponent::AddPartialFile).

If a file is added as a differenced file, the writer establishes criteria by which the requester should decide whether or not to actually copy a file to a backup medium. A writer typically adds differenced files to the Backup Components Document for inclusion in a backup PostSnapshot event (see CVssWriter::OnPostSnapshot). See Incremental and Differential Backups for details.

When a writer sets a shadow copy-required value of the VSS_FILE_SPEC_BACKUP_TYPE enumeration, it indicates that the file set should be backed up from a shadow-copied volume. File sets not tagged with a shadow copy-required value can be backed up from the original volume.

Writers set VSS_FILE_SPEC_BACKUP_TYPE values while handling an Identify event (see CVssWriter::OnIdentify).

A bit mask (or bitwise OR) of VSS_FILE_SPEC_BACKUP_TYPE values can be applied to a file set when adding it to a component using the IVssCreateWriterMetadata::AddFilesToFileGroup, IVssCreateWriterMetadata::AddDatabaseFiles, or IVssCreateWriterMetadata::AddDatabaseLogFiles method.

If no explicit file specification backup type is supplied during the addition of a file specification to a component, the specification is tagged with the default VSS_FILE_SPEC_BACKUP_TYPE value: (VSS_FSBT_ALL_BACKUP_REQUIRED | VSS_FSBT_ALL_SNAPSHOT_REQUIRED).

Requesters or writers can recover a file set's file specification backup type by using the IVssWMFiledesc::GetBackupTypeMask method.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2003 [desktop apps only]
Header vss.h

See also

IVssComponent::AddDifferencedFilesByLastModifyTime

IVssComponent::AddPartialFile

IVssCreateWriterMetadata::AddDatabaseFiles

IVssCreateWriterMetadata::AddDatabaseLogFiles

IVssCreateWriterMetadata::AddFilesToFileGroup

IVssWMFiledesc::GetBackupTypeMask

Incremental and Differential Backups