Backup and Restore Parameters

Applies to: Windows | Windows Server

Backup and Restore Parameters

This topic contains parameters that are used for backup and restore.

JET_paramAlternateDatabaseRecoveryPath
113

The full path to each database is persisted in the transaction logs at run time. Ordinarily, these databases must remain at the original location for transaction replay to function correctly. This parameter can be used to force crash recovery or a restore operation to look for the databases referenced in the transaction log in the specified folder.

Label	Value
Default Value:	""
Type:	Folder Path (string)
Valid Range:	0 – 246 characters
Scope:	Instance
Set After JetCreateInstance:	Yes
Set after JetInit:	No
Affects Physical Layout:	No
Affects Reliability:	No
Affects Performance:	No
Affects Resources:	No
Availability:	Windows XP and later releases

JET_paramCleanupMismatchedLogFiles
77

This parameter controls the outcome of JetInit when the database engine is configured to start using transaction log files on disk that are of a different size than what is configured. Normally, JetInit will successfully recover the databases but will fail with JET_errLogFileSizeMismatchDatabasesConsistent to indicate that the log file size is misconfigured. However, when this parameter is set to true then the database engine will silently delete all the old log files, start a new set of transaction log files using the configured log file size, and return JET_errSuccess.

This parameter is useful when the application wishes to transparently change its transaction log file size yet still work transparently in upgrade and restore scenarios.

Label	Value
Default Value:	False
Type:	Boolean
Valid Range:	False, True
Scope:	Instance
Set After JetCreateInstance:	Yes
Set after JetInit:	No
Affects Physical Layout:	Yes
Affects Reliability:	No
Affects Performance:	No
Affects Resources:	No
Availability:	All

JET_paramDeleteOutOfRangeLogs
52

When this parameter is true, then any transaction log files found on disk that are not part of the current sequence of log files will be deleted by JetInit. This may be used to automatically clean up extraneous log files after a restore operation.

Windows XP:  Introduced in Windows XP.

Label	Value
Default Value:	False
Type:	Boolean
Valid Range:	False, True
Scope:	Instance
Set After JetCreateInstance:	Yes
Set after JetInit:	No
Affects Physical Layout:	Yes
Affects Reliability:	No
Affects Performance:	Yes
Affects Resources:	Yes
Availability:	Windows XP and later releases

JET_paramOSSnapshotTimeout
82

This parameter configures the amount of time allowed between a call to JetOSSnapshotFreeze and JetOSSnapshotThaw before a timeout occurs. Please see JetOSSnapshotFreeze and JetOSSnapshotThaw for more information. The timeout is in milliseconds.

Label	Value
Default Value:	20000 (Windows XP and Windows Server 2003); 70000 (Windows Server 2003 SP1)
Type:	Integer
Valid Range:	0 – 2147483647
Scope:	Global
Set After JetCreateInstance:	Yes
Set after JetInit:	Yes
Affects Physical Layout:	No
Affects Reliability:	No
Affects Performance:	No
Affects Resources:	No
Availability:	Windows XP and later releases

JET_paramZeroDatabaseDuringBackup
71

When this parameter is true then every page in a database that is undergoing a streaming backup will be scrubbed of deleted data. It is important to note that the database pages that are being scrubbed are on disk. The full data set is backed up prior to the scrub process.

Label	Value
Default Value:	False
Type:	Boolean
Valid Range:	False, True
Scope:	Instance
Set After JetCreateInstance:	Yes
Set after JetInit:	No
Affects Physical Layout:	No
Affects Reliability:	No
Affects Performance:	Yes
Affects Resources:	No
Availability:	Windows XP and later releases

Requirements

Requirement	Value
Client	Requires Windows Vista, Windows XP, or Windows 2000 Professional.
Server	Requires Windows Server 2008, Windows Server 2003, or Windows 2000 Server.
Header	Declared in Esent.h.

See Also

JetCreateInstance
JetInit
JetOSSnapshotFreeze
JetOSSnapshotThaw