Reducing SIMATIC PCS 7 Multiproject Archive Size and Configuring Multi-Volume Backups

In SIMATIC PCS 7, native multiproject archives (.zip) frequently grow to unwieldy sizes (tens or hundreds of gigabytes) because temporary runtime databases, WinCC Alarm Logging segments, and Tag Logging archives are inadvertently captured during the backup process. To reduce archive volume for FTP transfer or long-term storage: first, execute a clean project reorganization or purge historical runtime database segments (.mdf / .ldf) using the WinCC Project Duplicator or SQL detach utilities; second, configure SIMATIC Manager to automatically split the archive into multi-volume chunks (under Options > Customize > Archiving > Configuring) to fit external media or FTP upload file size limits.

Root Causes of Bloated Multiproject Archives in PCS 7

When executing File > Archive in SIMATIC Manager, the archiving engine compresses all files and directories residing within the multiproject structure. Engineering backups frequently balloon to massive file sizes due to:
1. Active WinCC Runtime Database Segments:
- If an engineer runs WinCC Runtime on an Engineering Station or OS Single Station, Microsoft SQL Server creates active historical database segments (.mdf and .ldf files) inside the project subdirectories:
* <OS_Project>\ArchiveManager\TagLoggingFast
* <OS_Project>\ArchiveManager\TagLoggingSlow
* <OS_Project>\ArchiveManager\AlarmLogging
- These runtime archive files can easily total 50 GB to 200 GB.
2. Orphaned Temporary and Compilation Files:
- Intermediate files generated during CFC compilation, OS compilation, and S7 cross-reference table indexing accumulate in project directories.
3. Database Fragmentation:
- Deleted blocks, unlinked variables, and deleted charts leave behind empty allocated database pages within the STEP 7 project database (.dbf / .s7p).

Purging WinCC Tag Logging and Alarm Logging Databases Prior to Archiving

Before creating an engineering archive intended for code versioning, off-site delivery, or FTP transfer, purge runtime archive databases using these approved methods:

Deactivate WinCC Runtime:
- Never archive an active WinCC runtime project. Ensure WinCC Runtime is closed on all local stations.
- Close WinCC Explorer to release SQL Server locks.
Purge Archive Segments:
- In Windows Explorer, navigate to the OS project directory: <Multiproject_Path>\<OS_Name>\ArchiveManager.
- Safely remove historical segment files (*_TLG_F_*.mdf, *_TLG_S_*.mdf, *_ALG_*.mdf and matching .ldf files).
- Alternatively, open WinCC Explorer > Tag Logging / Alarm Logging, navigate to Archive Configuration, and click Reset Archive to truncate database segments safely.
Perform 'Save As with Reorganization (Slow)':
- In SIMATIC Manager, open the project and select File > 'Save As...'.
- Check the box With Reorganization (Slow).
- Select a new directory location. This process rebuilds all project relational tables from scratch, discards deleted records, eliminates database fragmentation, and typically reduces project storage footprint by 30% to 60%.

Configuring Multi-Volume Archive Splitting in SIMATIC Manager

When uploading large archives to remote FTP servers, cloud repositories, or transferring via FAT32-formatted USB storage drives (which limit single files to 4 GB), configure SIMATIC Manager to split the archive:

In SIMATIC Manager, navigate to the menu bar and select Options > Customize.
Click the Archiving tab.
In the Archiving program group, verify that PKZip or WinZip (or internal archiving tool) is selected.
Click the Configuring... button next to the archiving program selection.
In the configuration dialog:
- Locate the Multi-volume archive or Span Disks option.
- Select the target volume split size (e.g., 650 MB for CD, 4000 MB for FAT32 USB, or custom split sizes like 100 MB / 500 MB for FTP servers).
Click OK to apply the configuration.
Execute File > Archive > Multiproject:
- SIMATIC Manager generates sequential archive segments (e.g. Project.z01, Project.z02, Project.zip).
- To retrieve the archive on the target station, select File > Retrieve, select Project.zip, and SIMATIC Manager automatically reassembles all sequential chunks.

Project Archiving Optimization and Volume Reduction Table

The following table summarizes optimization strategies and their impact on PCS 7 project backup size:

Optimization ActionTarget Directory / FunctionAverage Size ReductionImpact on Engineering IntegrityPurge ArchiveManager<OS_Dir>\ArchiveManager (Tag/Alarm Logging)80% to 95% reduction on active projectsZero impact on engineering logic; historical process data omittedSave As with Reorganization (Slow)Entire Multiproject database rebuild30% to 60% reductionConsolidates memory, defragments indices, removes deleted objectsDelete S7 Cross-Reference Cache<Project>\XRF folder100 MB to 500 MBZero impact; rebuilt automatically during next cross-reference queryPurge SIMIT / Virtual Controller TempSimulation workspace subfoldersVariable (1 GB to 10 GB)Keeps project code clean without bloating hardware backupsMulti-Volume SplittingOptions > Customize > ArchivingSplits output into manageable filesBypasses file system and network transfer upload size ceilings

Verification

To verify archive integrity and size reduction:
1. Compare the size of the original uncompressed multiproject folder against the resulting ZIP archive. A properly cleaned project should compress down to between 200 MB and 2 GB depending on plant size.
2. Verify multi-volume generation by checking that sequential files (*.z01, *.z02, *.zip) are present in the destination folder.
3. Perform a test retrieval in SIMATIC Manager:
- Select File > Retrieve and select the primary .zip file.
- Extract the project to a temporary directory (C:\Temp\TestRetrieve).
- Open the retrieved project in SIMATIC Manager.
- Check that all AS stations, OS projects, and Plant Hierarchy charts open without database errors or missing library warnings.

Limitations and Operational Precautions

When managing PCS 7 project archives:
1. Never Manually Delete SQL System Databases: When cleaning project directories, never delete the primary project database files located in the root of the OS folder (<OS_Name>.mdf and <OS_Name>.ldf). These contain the WinCC configuration data (tags, screens, alarms). Only purge files inside ArchiveManager.
2. Never Archive Over Slow Network Shares: Always archive to a local solid-state drive (SSD) before copying the resulting archive to network storage. Archiving directly across a network share can lead to timeout errors or archive file corruption.
3. Retrieving Multi-Volume Archives: All volume files (.z01, .z02, .zip) must reside in the exact same directory during retrieval. If one volume is missing, SIMATIC Manager will abort the extraction with an unrecoverable CRC error.

Engineer FAQ

Why is my PCS 7 backup over 100 GB even though I only have two PLCs?

This happens when WinCC Runtime was executed on the Engineering Station with Tag Logging or Alarm Logging enabled. Historical trend and alarm data stored in the ArchiveManager folder are included in the backup. Purge the ArchiveManager folder before archiving.

Does 'Save As with Reorganization (Slow)' delete any engineering data?

No. Reorganization only discards deleted blocks, optimizes internal database pointers, and eliminates unallocated white space. All active charts, hardware configurations, and WinCC screens are completely preserved.

Can I use standard 7-Zip or WinRAR to extract a PCS 7 multi-volume backup?

While modern archivers can extract the files, always use SIMATIC Manager's native 'File > Retrieve' function to ensure correct file attribute restoration and proper registry registration of the project.

How do I archive only the AS logic without the WinCC OS projects?

In SIMATIC Manager, select the individual AS project under the Multiproject tree, click 'File > Archive', and select 'Projects' instead of 'Multiproject'. This creates a lightweight backup of only the controller logic.