ISSUE
01/24/19 15:54:38 : <VSS> Add required backup volumes to snapshot set
01/24/19 15:54:38 : <VSS> IVssBackupComponentsEx4 interface was found
01/24/19 15:54:38 : <VSS> CSV SMB3 (\\zxcv\zxcv\) \\zxcv\zxcv\,
<Error> AddVolumesToSnapshotSetEvents: USNAPError! AddToSnapshotSet for volume \\zxcv\zxcv\ failed 8004230c
(VSS_E_VOLUME_NOT_SUPPORTED) Shadow copying the specified volume is not supported.
Please check Windows Events Log that Volume Shadow Copy Service and VSS Writers are operating properly.
If volume resides on SMB share, insure that the Microsoft 'File Server VSS Agent Service' role is installed on the SMB server.
01/24/19 15:54:38 : AddVolumesToSnapshotSetEvents: USNAPError! AddToSnapshotSet for volume \\zxcv\zxcv\ failed 8004230c
(VSS_E_VOLUME_NOT_SUPPORTED) Shadow copying the specified volume is not supported.
Please check Windows Events Log that Volume Shadow Copy Service and VSS Writers are operating properly.
If volume resides on SMB share, insure that the Microsoft 'File Server VSS Agent Service' role is installed on the SMB server.
<Error> CreateVSSSnapshot: USNAPError! AddVolumesToSnapshotSetEvents call failed.
01/24/19 15:54:38 : CreateVSSSnapshot: USNAPError! AddVolumesToSnapshotSetEvents call failed.
RESOLUTION
Technical Overview
VSS for SMB File Shares is an extension to the existing VSS infrastructure and consists of four parts:
• A new VSS provider named “File Share Shadow Copy Provider” (fssprov.dll). The File Share Shadow Copy Provider is invoked on the server running the VSS-aware application and manages shadow copies on remote Universal Naming Convention (UNC) paths where the application stores its data files. It relays the shadow copy request to File Share Shadow Copy Agents.
• A new VSS requestor named “File Share Shadow Copy Agent” (fssagent.dll). The File Share Shadow Copy Agent is invoked on the file server hosting the SMB 3.0 file shares (UNC path) storing the application’s data files. It manages file share to volume mappings and interacts with the file server’s VSS infrastructure to perform shadow copies of the volumes backing the SMB 3.0 file shares where the VSS-aware applications stores their data files.
• A new RPC protocol named “File Server Remote VSS Protocol” (MSFSRVP). The new File Share Shadow Copy Provider and the new File Share Shadow Copy Agent are using this new RPC based protocol to coordinate shadow copy requests of data stored on SMB file shares.
• Enhancements to the VSS infrastructure to support the new File Share Shadow Copy provider, including API updates.
The following steps describe the basic Shadow Copy sequence with VSS for SMB File Shares.
A. The Backup Server sends backup request to its Backup Agent (VSS Requestor)
B. The VSS Requestor gather writer information and normalizes UNC path(s)
C. The VSS Service retrieves the writer metadata information and returns it to the VSS requestor
D. The VSS Service sends Prepare Shadow Copy request to the VSS writers involved and the VSS writers flushes buffers and holds writes
E. The VSS Service sends the Shadow Copy creation request to the File Share Shadow Copy Provider for any UNC paths involved in the Shadow Copy Set
E.1. The File Share Shadow Copy Provider relays the Shadow Copy creation request to the File Share Shadow Copy Agent on each remote File Server involved in the Shadow Copy Set
E.2. The File Share Shadow Copy Agent initiates writer-less Shadow Copy creation request to the VSS Service on the File Server
E.3. The VSS Service on the File Server completes Shadow Copy request using the appropriate VSS hardware or system providers
E.4. The File Share Shadow Copy Agent returns the Shadow Copy path (Shadow Copy Share) to the File Share Shadow Copy Provider
F. Once Shadow Copy creation sequence completes on the Application Server, the VSS requestor on the Application Server can retrieve the Shadow Copy properties from the VSS Service
G. Based on the Shadow Copy device name from the Shadow Copy properties on the Application Server, the Backup Server can access the data on the Shadow Copy shares on the File Servers for backup. The Shadow Copy share will have the same permissions as the original share.
Once the Shadow Copy on the application server is released, the Shadow Copies and associated Shadow Copy shares on the file servers are destroyed.
If the shadow copy sequence fails at any point, the shadow copy sequence is aborted and the backup application will need to retry.
For additional details on processing a backup under VSS, see https://docs.microsoft.com/en-us/windows/win32/vss/overview-of-processing-a-backup-under-vss
For additional details on the File Server Remote VSS Protocol, which is being used by the File Share Shadow Copy Provider and File Server Shadow Copy Agent, see https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-fsrvp/dae107ec-8198-4778-a950-faa7edad125b
Requirements and supported capabilities
VSS for SMB File Shares requires:
- Application server and file server must be running Windows Server 2012
- Application server and file server must be domain joined to the same Active Directory domain
- The “File Server VSS Agent Service” role service must be enabled on the file server
- The backup agent must run in a security context that has backup operators or administrators privileges on both application server and file server
- The backup agent/application must run in a security context that has at least READ permission on file share data that is being backed up.
VSS for SMB File Shares can also work with 3rd party Network Attached Storage (NAS) appliances or similar solutions. These appliances or solutions must support SMB 3.0 and File Server Remote VSS Protocols.
VSS for SMB File Shares support:
- An application server configured as a single server or in a failover cluster
- File servers configured as a single server or in a failover cluster with continuously available or scale-out file shares
- File shares with a single link DFS-Namespaces link target
VSS for SMB File Shares has the following limitations:
- Unsupported VSS capabilities
- Hardware transportable shadow copies
- Writable shadow copies
- VSS fast recovery, where a volume can be quickly reverted to a shadow copy
- Client-Accessible shadow copies (Shadow Copy of Shared Folders)
- Loopback configurations, where an application server is accessing its data on SMB file shares that are hosted on the same application server are unsupported
- Hyper-V hosts based Shadow Copy of virtual machines, where the application in the virtual machine stores its data on SMB file shares is not supported.
- Data on mount points below the root of the file share will not be included in the shadow copy
- Shadow Copy shares do not support failover
NOTES
Source: https://blogs.technet.microsoft.com/clausjor/2012/06/14/vss-for-smb-file-shares/