While using the VSS backup option to back up complex applications, you may encounter issues with creating volume snapshot/shadow copy. This article provides instructions on how to troubleshoot and resolve such issues.
Follow these steps to troubleshoot issues with VSS backup in Acronis Backup (Acronis Backup & Recovery):
- Get familiar with VSS technology used in Acronis Backup (Acronis Backup & Recovery) in the About part.
- Check for known issues in the Known issues part.
- Follow to Troubleshooting part to troubleshoot and resolve the issue.
About VSS technology
Acronis Backup (Acronis Backup & Recovery) uses VSS technology to create consistent backup of complex applications.
A VSS backup solution consists of following parts:
- VSS service is responsible for the communication of all VSS components.
- VSS requestor is represented by Acronis Backup and Recovery Backup Task that initiates the VSS backup.
- VSS writer is a part of complex application that guarantees it's data consistency during backup.
- VSS Provider is a component that creates and manages the snapshots/shadow copies.
The VSS Providers available in Acronis Backup (Acronis Backup & Recovery) 12/12.5 are:
|Automatically select snapshot provider||Automatically select among the hardware snapshot provider, software snapshot providers, and Microsoft Software Shadow Copy provider.|
|Use Microsoft Software Shadow Copy provider||We recommend choosing this option when backing up application servers (Microsoft Exchange Server, Microsoft SQL Server, Microsoft SharePoint, or Active Directory).|
The VSS Providers available in Acronis Backup (Acronis Backup & Recovery) 11.5/11.7 are:
|Hardware/software - Select automatically||VSS will use the hardware-based provider that supports the source volume. If none is found, VSS will use Acronis VSS Provider.|
|Software - Select automatically||In most cases, VSS will use Acronis VSS Provider.|
|Software - Acronis VSS Provider||VSS will use Acronis VSS Provider for taking snapshots.|
|Software - System provider (selected by default)||VSS will use the system provider (Microsoft Software Shadow Copy provider) for taking snapshots. We recommend choosing the system provider when backing up application servers (Microsoft Exchange Server, Microsoft SQL Server, Microsoft SharePoint, or Active Directory).|
|Software - A software provider||In most cases, VSS will use the Microsoft Software Shadow Copy provider.|
|Hardware - Select automatically||VSS will use the hardware-based provider that supports the source volume. If no hardware-based provider is found, backups will be created by means of Acronis Backup (Acronis Backup & Recovery) 11.5 without taking snapshots.|
Detailed information about the VSS parts and their purpose can be found in this Microsoft TechNet Article: Volume Shadow Copy Service.
How to enable/disable VSS backup:
VSS backup is activated in default backup options.
- In order to enable the VSS backup go to Backup options -> Volume Shadow Copy Service -> Use Volume Shadow Copy Service and chose the VSS provider you want to use.
- In order to disable the VSS backup go to Backup options -> Volume Shadow Copy Service -> Do not use VSS.
See more about VSS backup technology in following articles:
|Creating Backup with Complex Applications Such As Microsoft SQL Server, Oracle or Microsoft Exchange Running on the Server||Complex application backup|
|Using Acronis True Image to Back Up a System with VSS||Acronis VSS Provider technology|
|Acronis Backup: Using Microsoft VSS instead of Acronis VSS||Backup options|
|Acronis Backup & Recovery 10: Using Microsoft VSS instead of Acronis VSS||Backup options|
|Compatibility of Acronis Backup & Recovery 10 with StorageCraft's ShadowProtect||Software compatibility issue|
|VSS Locks Partition after Running a Backup||
Partition lock after backup
Use the free Acronis VSS Doctor tool to diagnose and fix the most common problems with VSS.
In order for a VSS backup to function correctly, all of the following steps should be fulfilled. Complete all steps before proceeding to error troubleshooting step.
1.1 Windows VSS services should be running
Go to Start -> Run -> services.msc. The following Windows services should be set to Manual Start:
- Microsoft Software Shadow Copy Provider
- Volume Shadow Copy
Following Windows service should be set to Automatic start and running:
- COM+ Event System service
1.2 Volume with shadow storage should have sufficient free space
VSS creates shadows in the shadow storages for each volume. If the shadow storage is not pre-defined for the volume, by default it is temporary created during the shadow copy on the same volume. Every volume selected for backup (including recovery, boot and service partitions) should have sufficient space for the shadow storage and the shadow copy.
In order to check that the volume has enough space for the shadow copy, create a shadow copy using the tools integrated in Windows and make sure the shadow copy is created successfully. If required, move the shadow storage to another volume or free up space on the volume.
Go to My Computer -> Right click on any of internal volumes listed -> Configure Shadow Copies
Select the volume you want to check and click on Create shadow copy to confirm that there is sufficient free space on each volume. Otherwise set up the storage area for the volume. You can also use the vssadmin utility to run this check and create,increase or relocate the shadow storage.
Go to Start -> Run -> diskmgmt.msc. Check the size of all volumes. If any volume of size 1024 MB or less is present on the disks, it will not be backed up via VSS, see this MSDN article for technical reference. Increase the size of such volume up to 1025 MB and more or exclude it from the backup source.
Go to Control Panel -> System - >System protection
Select the volume you want to check and click on > Create shadow copy to confirm that there is sufficient free space on each volume. Otherwise configure protection for the volume and increaze the size of the storage.
To check that the volume has enough free space and force the shadow copy creation, run the ntbackup utility and backup some data from the volume you want to check, checking the shadow copy creation. Run cmd and enter ntbackup.exe.
In case you have to create or increase the size of the storage, go to Control Panel -> System -> System restore and configure space for the storage.
1.3 Backup settings should be configured to use VSS snapshot
Go to Backup settings -> Volume Shadow Copy -> Select the VSS provider. For a Workstation OS select Software - System provider, as other providers can be used only on Server OS.
You need to have VSS snapshot enabled if you have databases running on your machine, otherwise you can set Do not use vss option.
Go to edit backup plan -> backup source and check the volumes selected for backup. If not all volumes are selected for backup, go to backup settings and deactivate the multi-volume snapshot. If you deactivate the multi-volume snapshot, make sure there is no data spanned across the volumes to have application-consistent backup.
1.4 VSS writers should be enabled and in consistent state
Go to Start -> Run -> cmd. Execute the command:
vssadmin list writers
Check all writers' state. If any writer shows the state different to stable, proceed to VSS writer error troubleshooting step.
In Windows Small Business Server 2003 Exchange VSS writer is disabled by default. Enable the writer to have Exchange database is consistent state.
- Click Start, click Run, type regedit, and then click OK.
- Locate and then double-click the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
- Double-click the Disable Exchange Writer value.
- In the Value data text box, change the value from 1 to 0, and then click OK.
- Quit Registry Editor.
- Click Start, point to Administrative Tools, and then click Services.
- Stop and then restart the Microsoft Exchange Information Store service.
If all steps above have been executed and issue still persists, go to error troubleshooting step.
2. Error troubleshooting
Analyze VSS errors to resolve the issue. Complete all steps before proceeding to collect information step.
2.1 Acronis Backup and Recovery backup errors
Find the log of the failed backup activity and check the error message. Go to known issues part and check for known solutions.
If a known solution has been applied, but the issue still persists, go to prerequisites step to troubleshoot the new issue.
If issue is not listed in known issues, proceed to windows errors step.
2.2 Windows errors
Go to Start -> Run -> eventvwr.msc. Navigate to Windows Logs -> Application and check for error messages related to VSS service. Search for solution in Microsoft Support articles, for example see this Microsoft TechNet Article.
Go to Windows Logs -> System and check for error messages related to VSS service.
Go to known issues part and check for known solutions.
If issue is not listed in known issues and persists, proceed to the next step.
2.3 VSS writer errors
Go to Start -> Run -> cmd. Execute the command
vssadmin list writers
If a writer is in "retryable" error state, restart this writer service and retry the backup.
Validate the writer:
If the writer still produces the error, then perform a backup with this VSS writer usage initiated with other VSS provider to ensure it's validity.
For Windows Server 2008, 2008R2, 2012, 2012R2, 2016 create a snapshot using Diskshadow tool to check the functionality of the VSS service components. If issue occurs on Workstation OS, skip this step.
If any writer fails with an error or creating a snapshot with Diskshadow does not end with "Number of shadow copies listed: x", you need to troubleshoot this writer and make sure it is functioning correctly before using VSS backup in Acronis Software. Acronis Backup relies on VSS to perform backup operations and correct functioning of VSS writers is a prerequisite for successful snapshot creation.
Deactivate the writer:
Deactivate the faulty writer. Go to Start -> Run -> services.msc, find the service for the particular writer and set it's start type to disabled, stop the service. Retry the backup. If backup succeeds, the writer causes the failure and issue should be addressed to the vendor of the writer. Deactivating the writer will lead to inconsistent backup of the application this writer was developed for.
To confirm the malfunctioning of the writer caused by the Acronis Backup (Acronis Backup & Recovery), go to collect information step.
If all steps above have been executed and issue still persists, go to collect information step.
3. Collect information
Collect following information and contact Acronis Customer Central.
3.1 SnapAPI logs
Collect SnapAPI logs:
For other products contact Acronis Customer Central.
3.2 VSS logs
Collect the output of vssadmin utility for basic VSS troubleshooting:
Collect AcronisInfo from the machine with the VSS backup issue:
3.4. Result of backup with Diskshadow (as screenshots or output to file)
When VSS backup fails, you can always create a consistent backup of applications suspending them before snapshot and starting them right after using batch files.