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Siemens AG
Entry type: FAQ Entry ID: 109804051, Entry date: 11/25/2021
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How do you clear your SFCache when there are problems archiving the values from the PCS 7 OS in the Process Historian?

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Here is the correct procedure for clearing the SFCache (Store & Forward Cache) on both single stations and redundant servers.

Deleting the SFCache on redundant servers

Disconnect OS server and Process Historian

  1. Disable the OS Runtime on the OS Standby server.
  2. On the Standby server, rename the "Processhistorian.cfg" file to "Processhistorian_old.cfg". This file is located in the WinCC project folder in which the WinCC project file is also located.
  3. Restart the OS Standby server.
  4. Enable the OS Runtime on the Standby Server.
  5. Wait until the redundancy alignment of the servers is finished. 
  6. Disable the OS Runtime of the Master OS.
  7. Rename the "Processhistorian.cfg" file on the master OS to "Processhistorian_old.cfg".
  8. Restart the OS Master server.
  9. Start the OS Runtime on the OS Master server.

Delete the SFCache

  1. Create a "Backup" folder (C:\ProgramData\Siemens\Backup). 
  2. In the backup folder, place a copy of the SFCache folder (C:\ProgramData\Siemens\SFCache\) with all the data and subfolders.
  3. In the backup folder, place a copy of the PH-Ready folder (C:\ProgramData\Siemens\PH-Ready\) with all the data and subfolders. (Some versions of PH do not have this folder, so this step is not applicable).
  4. First delete the contents of the original SFCache folder and then delete the contents of the PH-Ready folder on both the OS Master and the Standby server. When deleting, be sure to follow the correct order:
    • First in "C:\ProgramData\Siemens\SFCache\"
    • Then in "C:\ProgramData\Siemens\PH-Ready\" (Some versions of PH do not have this folder, so this step is not applicable.)

You are now running the OS server without SFCache.
No data is transmitted to the Process Historian and therefore no data is archived.

Reconnect the Process Historian to the OS

  1. Change the name of the file "Processhistorian_old.cfg" on the OS Standby server back to "Processhistorian.cfg". 
  2. Change the name of the file "Processhistorian_old.cfg" on the OS Master server back to "Processhistorian.cfg".
  3. Disable the Runtime on the OS Standby server.
  4. Enable the Runtime on the OS Standby server.
  5. Wait until the redundancy alignment of the servers is finished.
  6. Disable the Runtime on the OS Master server.
  7. Enable the Runtime on the OS Master server. After this step, you have a new empty SFCache available.
  8. Restart the Process Historian and check whether the PH now archives the OS data correctly again. If this is the case, you can delete the backup folder.

Deleting the SFCache on a single station

Disconnect OS and Process Historian

  1. Disable the OS Runtime.
  2. In the WinCC project folder you change the name of the file "Processhistorian.cfg" to "Processhistorian_old.cfg" and in doing make a backup of the data. This file is located in the WinCC project folder where the WinCC project file is also located.
  3. Restart your computer.
  4. Enable the WinCC Runtime again.

Delete the SFCache

  1. Create a "Backup" folder (C:\ProgramData\Siemens\Backup). 
  2. Place a copy of the SFCache folder (C:\ProgramData\Siemens\SFCache\) in the backup folder including all the data and subfolders.
  3. In the backup folder, you place a copy of the PH-Ready folder (C:\ProgramData\Siemens\PH-Ready\) with all the data and subfolders. (Some versions of PH do not have this folder, so this step is not applicable.)
  4. Delete the contents of the original SFCache and PH-Ready folders. Be sure to follow the correct order: 
    • First in "C:\ProgramData\Siemens\SFCache\"
    • Then in "C:\ProgramData\Siemens\PH-Ready\" (Some versions of PH do not have this folder, so this step is not applicable.)

You are now running your OS server without SFCache.
No data is transmitted to the Process Historian and therefore no data is archived.

Reconnect the Process Historian to the OS

Proceed as follows to re-establish communication with the Process Historian.

  1. Change the name of the file "Processhistorian_old.cfg" back to "Processhistorian.cfg".
  2. Disable the Runtime.
  3. Enable the Runtime again. After this step, you have a new empty SFCache available.
  4. Restart the Process Historian and check whether the PH now archives the OS data correctly again. If this is the case, you can delete the backup folder.


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