Archiving Large SIMATIC PCS 7 Multiprojects: Comparing PKZIP, WinZip, and Native 7-Zip Support

To archive large SIMATIC PCS 7 multiprojects efficiently without risking data corruption, engineers must adhere to version-specific archiving protocols. In PCS 7 versions prior to V8.2, Siemens officially supported only PKZIP (pkzipc.exe) for multiproject archiving and retrieval; utilizing third-party compression utilities (such as WinZip or custom batch wrappers) risked corrupting STEP 7 database structures and stripping mandatory file attributes. Beginning with SIMATIC PCS 7 V8.2, Siemens integrated native multi-threaded 7-Zip support directly into SIMATIC Manager (File -> Archive / Retrieve). For systems on older releases experiencing slow archiving, the approved practice is to perform project reorganization (File -> Save As... with Reorganization) and archive individual subprojects rather than executing unvalidated external compression scripts.

The Engineering Challenge of Large Multiproject Archiving

In SIMATIC PCS 7 engineering environments, multiprojects frequently grow to immense proportions—often exceeding 10 to 30 GB in total directory size. A standard multiproject contains multiple automation station (AS) projects, redundant operator station (OS) projects, batch recipes, route control databases, and thousands of CFC/SFC charts.

Executing File -> Archive from SIMATIC Manager is mandatory for project backups because:
1. It systematically detaches local SQL Server databases (.mdf/.ldf) associated with WinCC OS projects.
2. It packages all subprojects, libraries, and cross-project references into a single cohesive archive file.
3. It guarantees that file permissions, directory hierarchy, and internal STEP 7 database links remain intact.

However, on older PCS 7 versions, archiving a large multiproject could take 45 to 90 minutes, leading engineers to seek faster alternative compression utilities like 7-Zip.

Legacy PKZIP Constraints vs Third-Party Compression Risks

Prior to PCS 7 V8.2, SIMATIC Manager relied on the command-line archiver PKZIP (pkzipc.exe):

Limitations of PKZIP

Single-Threaded Architecture: PKZIP utilizes only a single CPU core, completely underutilizing modern multi-core engineering workstations.
Memory and Compression Limits: Deflate compression in older PKZIP implementations exhibits slow throughput on large binary files and SQL database containers.

Risks of Unofficial Third-Party Hacks

Some engineering teams developed custom batch scripts to intercept calls to pkzipc.exe and redirect arguments (pkzipc -a -r -p) to external archivers like 7z.exe or WinZip. Siemens explicitly warned against this practice for older releases because:
* External archivers often fail to preserve special DOS file attributes or handle open file descriptors properly.
* Compression algorithms other than standard PKZIP ZIP format (e.g., complex LZMA2 solid archives) frequently corrupted internal STEP 7 cross-reference pointers, causing project retrieval failures.
* Siemens Technical Support rejects service requests involving projects corrupted by unapproved compression utilities.

Native 7-Zip Integration in SIMATIC PCS 7 V8.2 and Later

Recognizing the necessity for high-speed archiving on modern hardware, Siemens officially integrated 7-Zip into SIMATIC PCS 7 starting with V8.2:

Native Implementation: SIMATIC Manager natively invokes an optimized, multi-threaded 7-Zip compression engine.
Multi-Core Utilization: 7-Zip automatically scales across all available physical and logical CPU cores, drastically accelerating compression and decompression.
Archive Formats: Supports standard .zip containers as well as .7z high-compression formats directly within the SIMATIC Manager GUI.
Data Integrity Assurance: The integrated engine guarantees that all WinCC SQL detachment routines, CFC block references, and multi-project header files are preserved with 100% fidelity.

Upgrading to PCS 7 V8.2 or higher provides a 4x to 8x speed improvement in project archiving without compromising system supportability.

Optimization Best Practices for Pre-V8.2 Multiproject Archiving

For engineering teams operating on PCS 7 V7.1, V8.0, or V8.1 who cannot immediately upgrade to V8.2, follow these proven best practices to minimize archiving duration:

1. Perform Project Reorganization

Before archiving, execute:
SIMATIC Manager -> File -> Save As... with 'With reorganization (slow)' checked.
This purges deleted block fragments, clears database whitespace, and compacts the project, often reducing archive size by 30% to 50%.

2. Exclude Temporary and Diagnostic Files

Ensure that temporary picture files (~*.pdl, *.tmp), diagnostic logs (WinCC\Diagnose\*.log), and obsolete SQL backups are purged from the project directories before compression.

3. Archive Subprojects Separately

In a large multi-user engineering project, archive individual AS projects and OS projects independently, rather than compressing the entire multi-project monolithically during daily routine backups. Archive the master multi-project container only during major version milestones.

Archiving Tool Performance and Support Matrix

The following table compares the archiving mechanisms across SIMATIC PCS 7 versions:

Archiving EngineSupported PCS 7 VersionsMulti-Threading SupportTypical 10 GB Archive TimeSiemens Official Support StatusPKZIP (pkzipc.exe)PCS 7 V6.x – V8.1No (Single-core)~45 – 70 minutesOfficially supported on legacy versionsUnofficial 7-Zip RedirectUnofficial hack (Pre-V8.2)Yes (Multi-core)~10 – 15 minutesUnsupported; risk of database corruptionNative 7-Zip EnginePCS 7 V8.2 and laterYes (Full multi-core)~8 – 12 minutesFully supported and certifiedWinZipV6.x (Limited)Partial~30 – 50 minutesDeprecated; risk of data loss on multiprojects

Adhering to factory-certified archiving tools safeguards critical engineering assets against data loss.

Verification

To verify that an archived project can be safely restored:
1. In SIMATIC Manager, execute File -> Archive and create the backup file.
2. Transfer the archive file to a separate, isolated engineering test workstation.
3. In SIMATIC Manager, execute File -> Retrieve and extract the project.
4. Open the retrieved project; verify that all AS projects and OS projects open cleanly.
5. In CFC, perform a consistency check (Options -> Check Consistency).
6. In WinCC Explorer, verify that the OS project opens without database attachment warnings.

Limitations and Operational Precautions

Never use external archiving tools (e.g., right-clicking a project folder in Windows Explorer and selecting 'Send to compressed folder') while SIMATIC Manager or WinCC is open; doing so corrupts locked SQL databases.
Do not interrupt an active archiving or retrieval process; terminating the process prematurely leaves corrupted database lock files.
Ensure target storage drives have adequate free disk space (at least 3x the uncompressed project size) to accommodate temporary staging files during compression.
Always store critical plant archives on redundant, off-site enterprise storage or version control repositories.

Engineer FAQ

Can I open a .7z archive created in PCS 7 V8.2 on a PCS 7 V8.1 system?

No. PCS 7 V8.1 does not have the native 7-Zip decompression engine in SIMATIC Manager. Furthermore, projects created or updated in V8.2 cannot be opened directly in V8.1 due to database schema updates.

Why does Windows Explorer built-in ZIP corrupt PCS 7 projects?

Windows Explorer ZIP compression cannot safely detach running Microsoft SQL Server instances (.mdf/.ldf) and fails to handle STEP 7 internal hidden file structures, corrupting the database upon restoration.

Does project reorganization delete actual user logic or tags?

No. 'Save As... with reorganization' only removes orphaned records, deleted blocks, and temporary index gaps. It preserves all active charts, tags, hardware configurations, and symbols.

Technical References

Related Tags

PCS 7 Archiving
7-Zip Integration
PKZIP
Multiproject Backup
Save As Reorganization

Save As Reorganization

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Archiving Large SIMATIC PCS 7 Multiprojects: Comparing PKZIP, WinZip, and Native 7-Zip Support