Snapshot microsoft volume shadow copy service vss

It also specifies the needed backup options and parameters as part of this document. For the SQL writer, each database instance that needs to be backed up is a separate component.

This is an XML document created by a requestor using the IVssBackupComponents interface in the course of setting up a restore or backup operation. The Backup Components Document contains a list of those explicitly included components, from one or more writers, participating in a backup or restore operation. It does not contain implicitly included component information. In contrast, a Writer Metadata Document contains only writer components that may participate in a backup.

Prebackup tasks under VSS are focused on creating a shadow copy of the volumes containing data for backup. The backup application will save data from the shadow copy, not the actual volume. Requestors typically wait on writers during preparation for backup and while the shadow copy is being created. If the SQL writer is participating in the backup operation, it needs to configure its files and also itself to be ready for backup and shadow copy. The SQL writer will detect torn databases with backing volumes outside the snapshot set and fail the backup during the PostSnapshot event.

In this phase, the requestor can move the data to a backup media, if needed. Interactions in this stage are between the requestor and the VSS framework. The SQL writer is not involved.

This is also the time at which the SQL writer can commit the backup as a differential base, if the current backup is a full backup of the database and not a copy-only backup. The requestor should send this event Backup Complete event explicitly to allow the SQL writer to commit differential base backups.

If this event is not received, the backup that is created will not be an eligible "differential base" backup. The requestor should save the Backup Component Document and each component backup metadata along with the data backed from the snapshot.

The only extension of the component set structure in SQL Server is the introduction of full-text catalogs. Full-text catalogs are container directories, which cannot be expressed as the VSS database or log files, given that the VSS database and log files do not have recursive specification. The snapshot creation phase is fast less than 60 seconds , to prevent blocking of all writes to the database. Post-snapshot If autorecovery is needed for the snapshot, the SQL writer will do the autorecovery for each database that has been selected to be in the snapshot.

For a detailed explanation, see Auto-Recovered Snapshots. The following figure shows the dataflow diagram during a VSS restore operation. To more fully understand the basic tasks involved in performing a restore, it is useful to break down this overview into the following topics:.

Between these two phases, the backup application is responsible for moving the relevant data around underneath SQL. During the initialization phase of a restore, the requestor needs to have access to the stored Backup Components Documents. The Backup Component Document that is generated during the backup operation, is stored as part of the backup data.

The backup application needs to pass this data back to the VSS framework. The SQL writer obtains access to this data at the beginning of the restore process. In preparing for a restore, a requestor uses the stored Backup Components Document to determine what is to be restored and how.

The requestor will select the components to be restored and set appropriate restore options as needed. If a backup application intends to apply differential or log backups on top of the current restore operation i.

The SQL writer will examine the supplied Backup Component Document to identify the appropriate databases, deleting any additional files created since the backup time.

It also checks disk spaces and closes any opened database file handles so that the requestor can copy the needed data during the Restore phase. This phase allows any early error conditions to be detected before the requestor does the actual file copying. SQL Server will also put the database in restoring state. From this point on, the database cannot be started until a successful restore. This is purely a requestor-specific action. It is the responsibility of the requestor backup application to copy the needed database files or copy relevant ranges of data for differential restores to the appropriate places.

The SQL writer is not involved in this operation. Once all the data is restored to the right places, a call from a requestor notifying that the restore operation has been completed IvssBackupComponents::PostRestore , will let the SQL writer know that Post Restore actions can be started. The SQL writer at this point will do the Redo phase of crash recovery. If recovery is not requested that is, SetAdditionalRestores true is not specified by the requestor , the undo phase of the recovery step is also carried out during this phase.

The SQL writer could be involved in the volume shadow copy creation process outside the context of backup and restore because the db files' backing volume s have been added into the volume snapshot set. The SQL writer supports full backup and restore operations in both noncomponent-based mode and component-based mode. In a noncomponent-based backup and restore, the requestor specifies a volume or a folder tree to be backed up and restored.

All the data in the specified volume and folder is backed up and restored. In a noncomponent-based backup, the SQL writer implicitly selects databases by using the list of volumes in the snapshot set. The writer checks for torn databases, raising an error if found. Roll forward differential or log restores after a restore is not supported through the SQL writer.

The requestor restores database s that have been backed up in noncomponent-based mode. Such restores cannot be followed up by a rollforward restore, such as log restore or differential restore. The files are copied in place and then the database s attached.

All this happens outside the scope of the SQL writer. In a component-based backup, all backing volumes for selected databases should be included in the volume snapshot set. Otherwise, the SQL writer will detect torn databases with backing volumes outside the snapshot set and fail the backup. A full backup backs up database data and all the log files necessary to bring the database up to a transactionally consistent state at restore time.

A full restore of the database backup is sometimes accomplished without doing any additional roll forwards. This may be because there is no metadata to facilitate the rollforward or, in some cases, roll forwards are not needed. Properly deleting a snapshot will also result in the snapshot LUs being removed from the target. The process is similar, except in this case no automatic deletion of the snapshot is performed by VSS.

In particular it cannot be used to gain access to the normal NAS server management console, either locally or remotely. Type vssadmin list shadows and hit Enter. Block unprivileged users from accessing to sensitive registry files.

You can use cmd or powershell. If there are any other partitions or volumes, please repeat this command and replace C: with other drive letters, D:, E:,for example. Check if there are still copyies left. Type vssadmin list shadows command and hit Enter. If all of them are deleted, you will get response "No items found that satisfy the query" from command prompt. Step 6.

Restart your computer and create a system restor point in the System Properties window. After these changes made, the newly created shadow copies should have the read-write permissions.

Also, you can check if your computer is affected again using icacls command. With which, you can not only enjoy the advantages of VSS, but also overcome its problem, such as, the shadow copy may be deleted due to Volume Shadow Copy Windows 10 high disk usage, etc.

For advanced users, you can use its professional version. It is able to delete old backup images with Backup Scheme, restore Windows backup to dissimilar hardware , for example, different CPU, with Universal Restore, etc. Can't afford data loss? Please download this software and create a backup just in case.

Content of this article: What is Volume Shadow Copy? Click Create to enable volume shadow copy in Windows Select the correct version of file or folder to restore. How to easily backup files and folders in Windows 10 with VSS As mentioned earlier, the volume shadow copy does help to backup files or volumes and you need to make use of a trust and reliable backup software like AOMEI Backupper Standard. It can backup files in partitions with other file systems, and also make up for its other shortcomings.

When all the components support VSS, you can use them to back up your application data without taking the applications offline.

VSS coordinates the actions that are required to create a consistent shadow copy also known as a snapshot or a point-in-time copy of the data that is to be backed up. The shadow copy can be used as-is, or it can be used in scenarios such as the following:.

You want to back up application data and system state information, including archiving data to another hard disk drive, to tape, or to other removable media. VSS service Part of the Windows operating system that ensures the other components can communicate with each other properly and work together.

VSS requester The software that requests the actual creation of shadow copies or other high-level operations like importing or deleting them. Typically, this is the backup application. VSS writer The component that guarantees we have a consistent data set to back up. VSS writers for various Windows components, such as the registry, are included with the Windows operating system.

Non-Microsoft VSS writers are included with many applications for Windows that need to guarantee data consistency during back up. VSS provider The component that creates and maintains the shadow copies. This can occur in the software or in the hardware. The Windows operating system includes a VSS provider that uses copy-on-write.

A hardware provider offloads the task of creating and maintaining a shadow copy from the host operating system. The following diagram illustrates how the VSS service coordinates with requesters, writers, and providers to create a shadow copy of a volume.

This section puts the various roles of the requester, writer, and provider into context by listing the steps that need to be taken to create a shadow copy. The following diagram shows how the Volume Shadow Copy Service controls the overall coordination of the requester, writer, and provider.

The requester asks the Volume Shadow Copy Service to enumerate the writers, gather the writer metadata, and prepare for shadow copy creation. Each writer creates an XML description of the components and data stores that need to be backed up and provides it to the Volume Shadow Copy Service. The writer also defines a restore method, which is used for all components.

The Volume Shadow Copy Service provides the writer's description to the requester, which selects the components that will be backed up. The Volume Shadow Copy Service notifies all the writers to prepare their data for making a shadow copy. Each writer prepares the data as appropriate, such as completing all open transactions, rolling transaction logs, and flushing caches.

When the data is ready to be shadow-copied, the writer notifies the Volume Shadow Copy Service. The application freeze is not allowed to take longer than 60 seconds. The Volume Shadow Copy Service flushes the file system buffers and then freezes the file system, which ensures that the file system metadata is recorded correctly and the data to be shadow-copied is written in a consistent order.

The Volume Shadow Copy Service tells the provider to create the shadow copy. At this point applications are free to resume writing data to the disk that is being shadow-copied. The shadow copy creation can be aborted if the writers are kept in the freeze state for longer than 60 seconds or if the providers take longer than 10 seconds to commit the shadow copy. The requester can retry the process go back to step 1 or notify the administrator to retry at a later time. If the shadow copy is successfully created, the Volume Shadow Copy Service returns the location information for the shadow copy to the requester.

In some cases, the shadow copy can be temporarily made available as a read-write volume so that VSS and one or more applications can alter the contents of the shadow copy before the shadow copy is finished.

After VSS and the applications make their alterations, the shadow copy is made read-only. This phase is called Auto-recovery, and it is used to undo any file-system or application transactions on the shadow copy volume that were not completed before the shadow copy was created. A hardware or software shadow copy provider uses one of the following methods for creating a shadow copy:.

Complete copy This method makes a complete copy called a "full copy" or "clone" of the original volume at a given point in time.

This copy is read-only. Copy-on-write This method does not copy the original volume. Redirect-on-write This method does not copy the original volume, and it does not make any changes to the original volume after a given point in time. Instead, it makes a differential copy by redirecting all changes to a different volume. After the mirror connection is broken, the original volume and the shadow copy volume are independent. The shadow copy storage area can be on the same volume or a different volume.

This preserves a copy of the data block on the original volume before the change overwrites it.