Very often we come across issues, in which the VSS Writers keep failing after two or three backups. It may be a single VSS Writer or many of them from the list we get on running "vssadmin list writers". I have been analyzing some tasks and have found that in cases where after updating the drivers for VSS, deleting the Subscriptions key and re-registering the DLL's, if we still find that the VSS writers fail, then it is not the writers which are at fault.
It is the Providers. Any transaction has to go through this service. On a Server, we have a database for everything. If we further add Exchange, database for Exchange is created.
VSS Writers are the ones who prepare the database for a snapshot shadow copy creation. Again, VSS Writers do not take snapshots. They just prepare the database for a snapshot creation. If we take a snapshot without preparing them first, the snapshot might be corrupt due to open transactions. For a perfect snapshot, these open transactions have to be closed first. The data in memory has to be flushed and further transaction have to stopped before a snapshot creation can happen.
It comes with the package of the individual component. Same goes for Exchange Writers. The writers will not interfere with each other as they are only responsible for their own database. Now, these are the ones responsible for taking a snapshot. It is the most important part of a shadow copy creation. If we add a backup program like StorageCraft, then a provider from StorageCraft named "StorageCraft Shadow Copy Provider" will be installed on top of the default provider and will be used as the default provider.
Further if we add Symantec Backup Exec, then a provider from Symantec will also be installed on top of the other two and will be used as the default provider.
Note: When we run the command "vssadmin list providers" - The one that comes up on the top of the list, is the one installed last, and is the one used by default. Sometimes, the providers may conflict or may malfunction. If the providers fail to do their job, it also affects the writers. It may cause the writers to fail too and generate event errors like Event id 8, in the event Viewer. Also known as NTFS. Without a file system, nothing is possible.
Further explanation not required for this. The VSS informs the respective writers that a snapshot creation is going to happen, so they must flush everything and freeze their databases for a a few seconds. The maximum time VSS writers can freeze their databases is for 60 seconds. The VSS then informs the providers to take a snapshot. A snapshot is taken which takes a maximum of 10 secs.
Once a snapshot is taken, it informs VSS that its job is done. Everything comes back to normal and the backup operation is started using the snapshot taken. In case of a backup failure, we must first check the drivers associated with the VSS backup. These drivers are :. If we have other providers installed, which could be StorageCraft provider, Symantec providers and Acronis Providers, we need to make sure that their files are also updated.
Others may also be there and we need to search it out. This step is performed only when we find the VSS writers in a failed state. If we find the writers stable and still backups fail, or we get errors, please do not perform this step.
In case, the VSS writers fail, we may delete the following registry key, after of course backing it up and reboot the server.
This key will automatically be re created on restart and writers should come back in stable state. Writers in Waiting for completion state is not a problem. This is as good as Stable. One more thing to note. If they fail repeatedly, then make sure that the application and its components are updated. Consult their respective engineers once. Make sure that the latest service packs and rollups are installed. Note: After deleting the Subscriptions key and rebooting, the subscriptions key is back in registry.
However when we do, vssadmin list writers, nothing may be listed. Therefore, even if Windows built-in VSS does not work, you have a second option. Download the free trial to have a try. Step 1. Connect the external drive, if any, to your computer. Step 3. The system drive is selected automatically. Click to select the destination backup storage. Then click Options. Step 4. By default, this software uses Windows built-in VSS. But you can switch to the other one. You can fix this error and continue use Windows backup utility, or you can find another reliable backup tool as well.
The ultimate goal is to solve the backup problem. Click the Start button then type CMD. When the command prompt icon appears, right-click it and select Run as Administrator. Type vssadmin list writers to find each of the VSS writers in a failed state. If the command hangs and does not return any output, this suggests the Volume Shadow Copy service or one of its dependent tasks might be in a bad state, causing the VSS writer audit to fail.
Figure 1: Admin command prompt. Restart the service to clear the failed state. If the service will not restart, reboot the production machine. Make a list or take a screenshot of all failed VSS writers. Open services. Re-run the command vssadmin list writers in an administrative command prompt to confirm the state has changed to Stable with no errors.
Figure 3: Stable VSS writer. Try another backup. If the VSS writers fail again, you must reboot the machine. Run the command vssadmin list writers. If there are some missing in the command prompt output, find the associated service in the table above and make sure it is started. Re-run vssadmin list writers in the same command prompt. Save the vshadow. Open an administrative command prompt and run the vshadow [volume] command for all volumes.
Figure 5: The vshadow command. Run the vssadmin list writers command to confirm that the VSS writers are now in a stable and ready state see Figure 1 above. Retry a backup. Skip to Navigation Skip to Main Content. Toggle SideBar.
Datto Help Center. Home More. Information Description. Environment Windows XP Windows 7 Windows Server Description There are three scenarios in which to use these instructions: Failed VSS Writers: Backups fail because an agent's VSS writers are in a failed state, but it is impossible or not desirable to restart the server until at least after business hours.
Running the command vssadmin list writers will only show a list of writers in a "started" state.
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