Product Documentation

Database Administrator's Guide

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VSS Configuration


With this option enabled, FairCom DB loads the Volume Shadow Copy Service (VSS) writer DLL (c-treeACEVSSWriter.dll) and initializes the VSS writer when the server starts. A FULL CONSISTENCY VSS backup of FairCom database files will be created, which is comparable to cleanly shutting down the FairCom server and then backing up all files.

For application files that are under full transaction control, a FULL CONSISTENCY VSS backup is more time-consuming and invasive than strictly required. Application files with the ctTRNLOG property are under full transaction control. If full transaction controlled files and the database transaction logs (L*.FCS and S0*.FCS) are included in backups, a normal database automatic recovery takes place at startup and will properly restore CRASH CONSISTENT backed up data. Do NOT enable VSS_WRITER YES in ctsrvr.cfg, on application files that are under full transaction control.

Note: VSS backups require the Volume Shadow Copy service to be running. If this Windows service is set to start manually or is off by default, it needs to be started before VSS backup will work.

The following message is logged in CTSTATUS.FCS indicating the VSS writer has been started:

Mon Sep 13 14:11:27 2010

- User# 00001 VSS Init: Successfully started the VSS writer.

If you run the command “vssadmin list writers” on a machine with FairCom DB Server running and a properly configured VSS, the list should include c‑treeACEVSSWriter.

Compatibility Notes

  • The FairCom VSS writer is compatible with the backup utilities provided in the server versions of Windows.
  • The Windows backup software provided in desktop versions of Windows (the Enterprise edition of Windows 7 and Windows 8) is not a VSS-compatible backup provider and therefore will not work with the FairCom VSS writer.
  • Windows Server backup (2008 & 2012) is a VSS provider and works with the FairCom VSS writer.
  • Acronis Backup has been tested on Windows 7 (both 32-bit and 64-bit) and works correctly with the FairCom VSS writer when configured with
  • The Novastor backup utility has been tested on non-server versions of Windows and works correctly with the FairCom VSS writer when configured with
  • Other third-party backup utilities may work with the FairCom VSS writer if they are VSS-compatible backup providers. Please check with the manufacturer of your backup utility for information about VSS compatibility.

User Permissions

FairCom VSS Writer is intended to be run by users with Administrator permissions. To avoid permission issues when running the VSS Writer with a user that is not an Administrator, you must perform the following operations on the Windows registry:

  1. Run the Windows regedit command.
  2. Browse to find the Key: HKEY_LOCAL_MACHINE>SYSTEM>CurrentControlSet>Services>VSS>VssAccessControl
  3. Insert a new REG_DWORD value with the following syntax DOMAINNAME\USERNAME. For example, if your domain is MYDomain and your user name is User, enter: MYDomain\User
  4. Set the newly created key to the hexadecimal value of 1.
  5. Restart the computer to apply the changes.

Files to Be Backed Up

The VSS writer needs a list of files that are considered as under the server's control. This information must be located in the file residing in the server's working directory (where the faircom.exe is located). For the VSS backup, only entries between !FILES and !END are relevant. There is no directory recursion, so wildcards will not be matched in subdirectories.








This information tells the backup utility which files are under FairCom DB control. If the set of files being backed up does not intersect with the set of files listed in, the VSS service does not interact with FairCom DB VSS writer, resulting in an invalid backup of any files open by the server.

While testing, it is recommended to run the FairCom DB SQL Server with DIAGNOSTICS VSS_WRITER in ctsrvr.cfg. When the VSS writer is correctly configured, you should see entries logged to CTSTATUS.FCS like those listed in VSS Diagnostic Logging.