For full-text catalog files, this backup should be done based on the file timestamps. This is described later in this document. A differential backup will always be with respect to the latest base backup that exists for the database.
At restore time, SQL Server will detect mismatched base and differential backups. So, it is responsibility of the backup application or system administrator to be sure that the differential is relative to the expected full backup. If some out of band procedure has made another full backup, the backup application may not be able to restore the differential, since it doesn't "own" the base backup. Currently if the byte-range information partial file information is too large exceeding 64 K bytes in buffer size , SQL Server will throw an error instructing the user to perform a full backup.
These files are included in the partial specification because every header of the SQL database file needs to be in the partial specification. Besides the header page, all the allocated pages need to be included in the partial specification.
After the base was taken, data files could be dropped. Such files are not included in the Writer Metadata Document during differential backup. Furthermore, there will not be partial information associated with the dropped file.
The partial information is not collected from the files until file shrinks have been disabled in the server. This ensures that we will never include any partial information that corresponds to the shrunk region of a data file. If growth took place before the partial information is collected, then the partial information should have included the allocated pages in the grown region. If the growth took place after the partial information is collected, then the partial information does not include changes in the grown region.
In the following sections, we will see that such changes will be restored by the log roll-forward. A logical rename of the file does not affect the backup or restore, since the file's logical name is not referenced anywhere in the Writer Metadata Document or in the Backup Component Document.
See the Writer Metadata document: An Example for more detail. A physical database file rename does not take effect until the database restarts. Therefore, the database configuration information or the file path information in the partial information buffer is still based on the old physical paths, which are the only valid paths to those database files on the snapshot.
During a differential restore, the backup metadata that the requestor gives back to the SQL writer has the backup type information. Therefore, no special treatment from the SQL writer is needed. SQL Server will figure out that it's a differential restore by itself.
SQL Server handles such a differential restore in the same way as against a native differential restore that is not performed through VSS.
During this phase SQL Server will resize all files to the appropriate size based on the differential backup's file metadata.
If the file is grown, SQL Server zeros out the grown portion. If a new file has to be created it was created after the base was taken , SQL Server zeros out the new file. It also closes all the file handles so that the backup application can overwrite the files with the restored data from the backup media. The client should restore the files based on the partial file specification.
Such files must have been pre-created by SQL Server during the restore preparation phase. They should have been extended to the right size and zeroed out. The client only needs to lay down the data as per partial specification the partial specification includes all allocated extents.
The partial information that SQL Server has provided does not include any tracking information for such file drops. SQL Server is responsible for detecting the files to be deleted, by comparing the restored files metadata against the existing containers, and actually deleting them.
This is done prior to the restore as a preparation step. Such files must have been extended to the right size by SQL Server during the restore preparation phase. The extended region must have been zeroed out by SQL Server as well. Therefore, the client can safely lay down the data even in the grown region as per partial specification. If the file was grown after the partial information was taken, the changes in the grown region will be restored by replaying the log that was backed up along with the differential backup.
SQL Server is responsible for truncating the file to the required size as per metadata. This would not affect the restore as the logical name does not appear in the Writer Metadata Document or the Backup Component Document. The logical name change will be restored when the client applies the change to the primary database file, which contains the system catalog information.
If by the time of differential backup, the rename had not taken effect, then the client still restores data to the old location. A database restart post-restore will cause the physical rename to take effect. If by the time of differential backup, the physical file rename had already taken effect, then the partial data, if any, was backed up from the new physical path. During the post restore events, the SQL writer will perform the normal redo operation and recovery if SetAdditionalRestores is set to False of the database.
SQL Server full-text catalogs are part of the database resources that need to be backed up or restored together with the rest of the database files. A differential backup is timestamp-based for full-text catalog. In other words, there will not be different bases for different containers. For VSS full-text catalog backup, this means for all full-text catalog containers, the differential backup will be single-timestamp based, unlike the case of native SQL differential backup, in which there is one timestamp base per full-text catalog container.
In VSS, this timestamp is expressed as a component-wide property that is set during the full backup, and used during a subsequent differential backup. This indicates to the backup application that the SQL writer owns the management of the differential base. The base timestamp is set during a full backup. The backup application will retrieve this timestamp from the base full backup, and make the timestamp available for the writer by calling IVssComponent::GetBackupStamp to retrieve the base stamp from the previous base backup.
Backup application's responsibility during differential backup During a differential backup, the backup application is responsible for:. Backup application's responsibilities during a differential restore During a differential restore, the backup application is responsible for:. It is sometimes necessary to take a backup that is intended for a special purpose.
For example, you might need to make a copy of a database for testing purposes. This backup should not impact the overall backup and restore procedures for the database. When a copy-only backup is selected, it is assumed that files on disk will be copied to a backup medium by the requestor regardless of the state of each file's backup history. SQL Server will not update the backup history.
This type of backup will not constitute as a base backup for further differential backup operations and also it does not disturb the history of the previous differential backups. The backup application is only allowed to specify new targets for the physical path, but not the file specification. A requestor may need to restore an SQL database with a new name, especially if the database is to be restored side by side with the original database.
The SQL writer will take the entire content of New Component Name's value and use it as the new name for the restored database. If no option is specified, SQL will restore the database with its original name component name.
The SQL writer currently does not support "Rename across Instances" to move a database to a new instance. Data in the snapshot cannot be safely accessed prior to going through the recovery phase to roll back in-flight transactions and placing the database in a consistent state.
Since the snapshot is in a read-only state, it cannot be recovered by the normal process of attaching the database. It is possible to autorecover the snapshots as part of the snapshot creation process. SQL Server the auto recovery should be applied only to app-rollback snapshots but not for backup snapshots. This process will do the following for each explicitly selected by the requestor SQL Server database in the snapshot set:. Attach the snapshot database to the original SQL Server instance that is, the instance to which the original database is attached.
Shrinking the log files is the default behavior. This can be disabled by setting the value to the following registry key to 1. This may be useful in scenarios where the snapshot may be used to export data from a specific page at a specific point in time from the log to fix a problem in the online database.
In some cases, the snapshot databases may contain some in-flight multi-database transactions. During recovery operation, the SQL writer will attach the database on the snapshots with the Presumed Abort option. This would roll back any multi-database transaction that is not yet committed including any transactions that are in a Prepared to Commit state.
This may lead to some inconsistencies between databases in the snapshot set. Sometimes, when you backup with Windows built-in tool but failed, you may receive Windows backup failed to read from the shadow copy error or VSS insufficient storage error, you can have an alternative way to backup your computer with VSS technology. It has embedded with VSS technology. It allows you to create system backup, disk backup, partition backup and file and folder backup. You can create backup to external hard drive and internal hard drive.
The best part is it is free to use. Step 2: Click Add disk to select the disk you need to backup. Then, click to select a location to save the backup. Step 3: Click Options to set up advanced settings.
It uses VSS provided by Microsoft by default. Tips: There are still some other settings you can set up. For example: click general to enable encryption for backups and enable email notification.
Click compression to choose the compression level for a backup. This allows arrays to recover very large data sets and resume normal operations in several seconds. In a LUN swap, the shadow copy is imported and then converted into a read-write volume. In LUN resynchronization, the shadow copy is not altered, so it can be used several times. In LUN swapping, the shadow copy can be used only once for a recovery.
For the most safety-conscious administrators, this is important. When LUN resynchronization is used, the requester can retry the entire restore operation if something goes wrong the first time.
For this reason, the shadow copy LUN must use the same quality of storage as the original production LUN to ensure that performance is not impacted after the recovery operation.
If LUN resynchronization is used instead, the hardware provider can maintain the shadow copy on storage that is less expensive than production-quality storage. All of the operations listed are LUN-level operations. If you attempt to recover a specific volume by using LUN resynchronization, you are unwittingly going to revert all the other volumes that are sharing the LUN.
Shadow Copies for Shared Folders uses the Volume Shadow Copy Service to provide point-in-time copies of files that are located on a shared network resource, such as a file server. With Shadow Copies for Shared Folders, users can quickly recover deleted or changed files that are stored on the network.
Because they can do so without administrator assistance, Shadow Copies for Shared Folders can increase productivity and reduce administrative costs. With a hardware provider that is designed for use with the Volume Shadow Copy Service, you can create transportable shadow copies that can be imported onto servers within the same subsystem for example, a SAN. These shadow copies can be used to seed a production or test installation with read-only data for data mining.
With the Volume Shadow Copy Service and a storage array with a hardware provider that is designed for use with the Volume Shadow Copy Service, it is possible to create a shadow copy of the source data volume on one server, and then import the shadow copy onto another server or back to the same server. This process is accomplished in a few minutes, regardless of the size of the data.
The transport process is accomplished through a series of steps that use a shadow copy requester a storage-management application that supports transportable shadow copies. Import the shadow copy to a server that is connected to the SAN you can import to a different server or the same server.
A transportable shadow copy that is created on Windows Server cannot be imported onto a server that is running Windows Server or Windows Server R2. A transportable shadow copy that was created on Windows Server or Windows Server R2 cannot be imported onto a server that is running Windows Server However, a shadow copy that is created on Windows Server can be imported onto a server that is running Windows Server R2 and vice versa.
Shadow copies are read-only. It works only if there is a hardware provider on the storage array. Shadow copy transport can be used for a number of purposes, including tape backups, data mining, and testing. In the case of a hard disk drive backup, the shadow copy created is also the backup. Data can be copied off the shadow copy for a restore or the shadow copy can be used for a fast recovery scenario—for example, LUN resynchronization or LUN swapping.
When data is copied from the shadow copy to tape or other removable media, the content that is stored on the media constitutes the backup. The shadow copy itself can be deleted after the data is copied from it.
It depends on the backup software that you used. Most backup programs support this scenario for data but not for system state backups.
It depends on the backup software you used. If you create a shadow copy on Windows Server , you cannot use it on Windows Server Also, if you create a shadow copy on Windows Server , you cannot restore it on Windows Server However, you should not do this. VSS is designed to create shadow copies of entire volumes. Temporary files, such as paging files, are automatically omitted from shadow copies to save space.
To exclude specific files from shadow copies, use the following registry key: FilesNotToSnapshot. The FilesNotToSnapshot registry key is intended to be used only by applications. Users who attempt to use it will encounter limitations such as the following:. Check the product support section of the Web site of the company that created the backup program. There may be a product update that you can download and install to fix the problem. If not, contact the company's product support department.
The shadow copy storage area or "diff area" is the location where the data for the shadow copy that is created by the system software provider is stored. The diff area can be located on any local volume. However, it must be located on an NTFS volume that has enough space to store it. If there is a preconfigured manual association between the original volume and the shadow copy volume location, then that location is used. If the previous two criteria do not provide a location, the shadow copy service chooses a location based on available free space.
If more than one volume is being shadow copied, the shadow copy service creates a list of possible snapshot locations based on the size of free space, in descending order.
The number of locations provided is equal to the number of volumes being shadow copied. If the volume being shadow copied is one of the possible locations, then a local association is created.
Otherwise an association with the volume with the most available space is created. However, persistent shadow copies can be made only for NTFS volumes. In addition, at least one volume mounted on the system must be an NTFS volume. The maximum number of shadow copied volumes in a single shadow copy set is Note that this is not the same as the number of shadow copies.
The max number is of software shadow copies for each volume is
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