Zip Engines
The plugin supports 3 engines for building the archive. Each has its own pros and cons.
ZipArchive (PHP native)
Pros:
- Built into PHP, no system command needed
- Standard
.zipformat - opens with any tool
Cons:
- Memory heavy - reads many files into RAM
- Archive size limit of roughly 2-4 GB depending on the build
- Slow on sites with many small files
When to use: small sites (<2 GB), shared hosting that does not allow exec().
DupArchive (the plugin's own)
Pros:
- Chunked - does not load the whole archive into RAM
- Supports unlimited size
- Can resume after a timeout
- Verifies integrity automatically
Cons:
- Its own
.dafformat - can only be extracted with the installer (this build ships no command-line extraction tool) - Slower than ZipArchive for very small sites
When to use: the default for most sites. Especially sites > 2 GB.
Shell Exec (calls the system zip)
Pros:
- Fastest for large sites with many files
- Minimal memory (the zip CLI streams)
- Standard
.zipformat
Cons:
- Requires the PHP function
exec()to be enabled - Requires the
zipbinary to be installed on the server - Does not support resume
When to use: a dedicated VPS where you have root, sites > 5 GB.
Change the engine
SL Migrations → Settings → Package → Archive Engine:
| Engine | Setting |
|---|---|
| ZipArchive | ZipArchive |
| DupArchive | DupArchive (default) |
| Shell Exec | ShellExec |
The plugin falls back automatically if the chosen engine is unavailable (for example ShellExec when the server has no zip).
Verify which engine is in use
Open the build log in Packages → click the package → View Log. Look for the line:
ARCHIVE Type=DUP Mode=DupArchive
Mode tells you which engine is in use.