PH server 2014+SP1+Upd1 on a PCS7v8.1SP1 system has gone to locked state because C:\ is full. The reason for it has become full is the system database msdb (MSDBData.mdf) that is currently >200Gb.

We once reduce the size of this with instructions found on Google and got PH active again, but after a while it has grown again. We seek for a better solution on to keep its size small. We will someday try to update PH to 2014SP3Upd1 if that solves this. Anyone know why is that so big and how can we get it to stay small with this version?

Update: 

Used a SQL query and found that 'dbo.backupfile' and 'dbo.backupfilegoup' has the most data

Got instructions from Siemens support:

guide how to shrink the msdb.

1. First of all shut down the PH database in the PH Management Console. Please perform this in the PH Management Console at "Process Historian Management". Here you can choose "shut down" in the drop down box and click on the button "Go".
2. As soon as the database is in the status "Idle", the PH Management Console can be closed
3. In the next step, please close the 2 symbols for the PH in the task bar (at the bottom right). (right-click -> close or exit)
   With PH 2014 just the Discovery Task could be closed.
4. Afterwards please stop the 4 PH Services: Process Historian Discovery Service, Process Historian Maintenance Service, Process Historian Redundancy Service and SIMATIC Process Historian in the Server-Manager
5. After this the both system databases could be moved to D drive (or another drive with more capacity) with the following procedure:
   • Open the SQL Server. You can open it at Start -> All Programs -> Microsoft SQL Server 2008 R2 -> SQL Server Management Studio
   • In the new window, click on "Connect" -> click on "New Query" in the menu bar of the SQL Server
   • Insert the content of the script "GetFileInfo.sql" to the new window on the right side of the SQL Server, to be able to note the current paths of the tempdb and the msdb. Please note these paths
   • In the next step open the script "MoveMSDB_TempDb.sql" and insert the new paths for these both databases. Execute this script as soon as you have inserted the new paths
   • Stop the service SQL Server (HISTORIAN) in the Server-Manager
   • Then move the database files of the tempdb and msdb from the C drive to the path, which you inserted in the script  "MoveMSDB_TempDb.sql"
   • Start the SQL Server service again
6. Execute the script "SQL_PH_MSDB_reduce_size.sql" (could take some time)
7. Wait until the script has been finished
8. Execute the script "ReduceMSDBJob.sql"
9. As soon as this has been finished you can move the system databases back to the C drive (as described in 4.)
10. Check, if the SQL Agent is started also in the services in the Server-Manager. If this service is not started, start this manually

Do a restart of the Process Historian

Edit:

Step 8:

8A. In "ReduceMSDBJob.sql" edit rows:

Ln13 N’<Computername>\<Windows username>’
Ln16 N’<Computername>\HISTORIAN’
Ln122 N’<Computername>\<Windows username>’

8B. Run "ReduceMSDBJob.sql"

8C. Right click msdb database and select Tasks>Shrink>Database

8D. Right click msdb database and select Tasks>Shrink>Files>Data

8E. Right click msdb database and select Tasks>Shrink>Files>Log