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.
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:
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 ctsrvr.dds 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 ctsrvr.dds, 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.