Compression

Overview

The backup program supports multiple compression formats. By default, it uses Zstandard (tar.zst) compression, which offers the best balance of compression ratio and speed.

Supported Formats

Format	Extension	Description	Use Case
tar.zst	.tar.zst	Default. Zstandard compression via Python 3.14 built-in	Best overall choice: fast and high compression
tar.gz	.tar.gz	Gzip compression	Wide compatibility, good balance
tar.bz2	.tar.bz2	Bzip2 compression	Higher compression, slower
tar.xz	.tar.xz	LZMA compression	Highest compression, slowest
tar	.tar	Uncompressed archive	Fast, no compression overhead
zip	.zip	ZIP archive with deflate	Cross-platform compatibility
gzip	.gz	Gzip single file	For single file backups only

Setting Compression Format

Use the BACKUP_COMPRESSION environment variable:

export BACKUP_COMPRESSION=tar.zst  # Default
python main.py

Format Details

Zstandard (tar.zst) - Recommended

export BACKUP_COMPRESSION=tar.zst

Advantages:

• Excellent compression ratio (similar to bzip2)
• Very fast compression and decompression
• Built into Python 3.14+ (no external dependencies)
• Modern, actively developed

Best for: Most use cases, especially large backups

Gzip (tar.gz)

export BACKUP_COMPRESSION=tar.gz

Advantages:

• Universal compatibility
• Good balance of speed and compression
• Standard on Unix systems

Best for: Maximum compatibility

Bzip2 (tar.bz2)

export BACKUP_COMPRESSION=tar.bz2

Advantages:

• Better compression than gzip
• Widely supported

Best for: When file size is more important than speed

LZMA/XZ (tar.xz)

export BACKUP_COMPRESSION=tar.xz

Advantages:

• Highest compression ratio
• Good for long-term archival

Best for: Maximum compression, infrequent access

Uncompressed Tar

export BACKUP_COMPRESSION=tar

Advantages:

• Fast backup and restore
• Preserves directory structure
• No CPU overhead

Best for: Fast local backups, pre-compressed data

ZIP

export BACKUP_COMPRESSION=zip

Advantages:

• Cross-platform (Windows, Mac, Linux)
• Individual file access without full extraction

Best for: Windows compatibility, heterogeneous environments

Gzip Single File

export BACKUP_COMPRESSION=gzip

Limitations:

• Only works for single file backups
• Raises error if source is a directory

Best for: Compressing individual large files

Compression Comparison

Based on typical mixed data (documents, code, configs):

Format	Relative Speed	Relative Size	CPU Usage
tar	⚡⚡⚡⚡⚡ Fastest	💾💾💾💾💾 Largest	▁ Minimal
tar.zst	⚡⚡⚡⚡ Very Fast	💾💾 Small	▃ Low
tar.gz	⚡⚡⚡ Fast	💾💾💾 Medium	▄ Medium
zip	⚡⚡⚡ Fast	💾💾💾 Medium	▄ Medium
tar.bz2	⚡⚡ Moderate	💾💾 Small	▆ High
tar.xz	⚡ Slow	💾 Smallest	▇ Very High

Recommendations

For Daily Backups

export BACKUP_COMPRESSION=tar.zst

Fast, efficient, modern default.

For Long-Term Archives

export BACKUP_COMPRESSION=tar.xz

Maximum compression for storage savings.

For Maximum Compatibility

export BACKUP_COMPRESSION=zip

Works everywhere, easy to extract.

For Fast Local Backups

export BACKUP_COMPRESSION=tar

No compression overhead, preserves directory structure.

Custom Archive Names

You can specify a custom archive name:

export BACKUP_ARCHIVE_NAME=myproject_backup
export BACKUP_COMPRESSION=tar.zst

This creates: myproject_backup.tar.zst

If not specified, the default format is:

backup_{source_dirname}_{timestamp}.{extension}

Example: backup_documents_20250109_143022.tar.zst