✎ [V8] ISSUE: Cannot start shadow copy (VSS_E_WRITERERROR_NONRETRYABLE) (MS SQL server with large number of databases) [Ahsay Wiki]

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===== [V8] ISSUE: Cannot start shadow copy (VSS_E_WRITERERROR_NONRETRYABLE) (MS SQL server with large number of databases)   =====

<html>
 <b>
  Article ID:
 </b>
 8086
 <br/>
 <b>
  Reviewed:
 </b>
 2020-11-10
 <br/>
 <br/>
 <b>
  Product Version:
 </b>
 <br/>
 AhsayOBM: 8.1.0.0 to 8.x
 <br/>
 OS: Windows
</html>


===== Problem Description =====
<html>
When performing either a scheduled or manual MS SQL database backup job, where there are a large number of databases selected in the backup source. The following backup error is received in the backup report:
 <br/>
 <table border="0" cellpadding="0" cellspacing="0" width="850">
  <tr>
   <td bgcolor="#E8E8E8" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-TOP: #C0C0C0  1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    No.
   </td>
   <td bgcolor="#E8E8E8" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-TOP: #C0C0C0  1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    Type
   </td>
   <td bgcolor="#E8E8E8" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-TOP: #C0C0C0  1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    Timestamp
   </td>
   <td bgcolor="#E8E8E8" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-TOP: #C0C0C0 1px solid; BORDER-RIGHT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    Log
   </td>
  </tr>
  <tr>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    *
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    ...
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    ...
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-RIGHT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    ...
   </td>
  </tr>
  <tr>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    *
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    info
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    ...
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-RIGHT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    [Start] Backing up database...
   </td>
  </tr>
  <tr>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    *
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    <font color=#FF0000>
     erro
    </font>
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    <font color=#FF0000>
     YYYY/MM/DD
     hh:mm:ss
     </font>
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-RIGHT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    <font color=#FF0000>
     Cannot start shadow copy, reason =The writer operation failed because of an error that might
<br>
recur if another shadow copy is created. (VSS_E_WRITERERROR_NONRETRYABLE)
     <br/>
    </font>
   </td>
  </tr>
  <tr>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    *
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    ...
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="top">
    ...
   </td>
   <td bgcolor="#ffffff" style="BORDER-LEFT: #C0C0C0 1px solid; BORDER-RIGHT: #C0C0C0 1px solid; BORDER-BOTTOM: #C0C0C0 1px solid" valign="middle">
    ...
   </td>
  </tr>
 </table>
</html>


===== Cause =====
<html>
The error message is returned by MS SQL VSS writer, suggesting that there was an insufficient number of worker threads configured on the MS SQL Server to support the backup all databases selected for backup.
 <br/>
 <br/>
A  MS SQL Server databases backup job using VSS requires three worker threads per database. For example, a 64 bit MS SQL server with 4 CPUs is automatically configured with 512 work threads, which implies that the maximum number of databases that can be selected for backup is 170.
 <br/>
 <br/>
 Please refer to the Limitations and Restrictions section in the following article for more details:
 <br/>
 <a class="postlink" href="https://msdn.microsoft.com/en-us/library/ms190219.aspx">
  https://msdn.microsoft.com/en-us/library/ms190219.aspx
 </a>
</html>


===== Resolution =====
<html>
To resolve this issue, either:
<br>

<ol>
<li><font color=black>Create additional backup sets (to be performed at different time) for the excess databases.
<br>
<br>
or

</font></li>
<br>

<li><font color=black>Increase the maximum number of worker threads on the MS SQL Server.
<br>
<br>
To configure the max worker threads option:
<br>
<br>
 <ul>
  <li>
   <font color=black>In the Object Explorer, right click a server and select <b>Properties</b>.</font>
  </li>
  <br>
  <li>
   <font color=black>Click the <b>Processors</b> node.</font>
  </li>
  <br>
  <li>
   <font color=black>In the <b>Max worker threads</b> box, type or select a value for the max worker thread.</font>
  </li>
 </ul>
<br>
<br>
For more details, refer to the following article: <a href="https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/configure-the-max-worker-threads-server-configuration-option">https://docs.microsoft.com/en-us/sql/database-engine/configure-windows/configure-the-max-worker-threads-server-configuration-option</a>
<br>
<br>
<font color=#FF0000>
Important:

<br>
Please consult with an experienced database administrator or certified SQL Server technician before making any change to the maximum worker threads.</font>


</font></li>
</html>


===== Keywords =====
mssql, sql, worker threads, max, databases
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