JetOSSnapshotPrepareInstance Function

Article
08/26/2021

Applies to: Windows | Windows Server

JetOSSnapshotPrepareInstance Function

The JetOSSnapshotPrepareInstance function selects a specific instance to be part of the snapshot session.

Windows Vista: JetOSSnapshotPrepareInstance was introduced in Windows Vista.

JET_ERR JET_API JetOSSnapshotPrepareInstance(
  __in          JET_OSSNAPID snapId,
  __in          JET_INSTANCE instance,
  __in          const JET_GRBIT grbit
);

Parameters

snapId

The identifier of the snapshot session.

instance

The instance that will be used for this call.

grbit

The options for this call. This parameter is reserved for future use. The only valid value is 0 (zero).

Return Value

This function returns the JET_ERR datatype with one of the following return codes. For more information about the possible ESE errors, see Extensible Storage Engine Errors and Error Handling Parameters.

Return code	Description
JET_errSuccess	The operation completed successfully.
JET_errInvalidParameter	The snapshot id pointer is NULL or the grbit parameter is invalid.
JET_errOSSnapshotInvalidSequence	A snapshot session is already in progress.
JET_errOSSnapshotInvalidSnapId	The identifier for the snapshot session is not valid.

If this function succeeds, the specified instance will be part of the snapshot session.

If this function fails, no change in the engine state occurs.

Remarks

The normal API sequence call is: JetOSSnapshotPrepare, optionally followed by one or more calls to JetOSSnapshotPrepareInstance, then followed by JetOSSnapshotFreeze. Once the freeze is started, it can be terminated using JetOSSnapshotThaw. At any time after the prepare, the snapshot session can be abruptly terminated with JetOSSnapshotAbort. Event log entries will be generated for the different steps of the snapshot.

If JetOSSnapshotPrepareInstance is not called between the start of the session (JetOSSnapshotPrepare) and the freeze moment (JetOSSnapshotFreeze), all the running instances in the engine will freeze and become part of the snapshot session. This occurs for two reasons:

It simplifies the code for users who want all instances.
It allows backward compatibility for the callers of the snapshot APIs.

Requirements

Requirement	Value
Client	Requires Windows Vista.
Server	Requires Windows Server 2008.
Header	Declared in Esent.h.
Library	Use ESENT.lib.
DLL	Requires ESENT.dll.

JetOSSnapshotPrepareInstance Function