When transferring thousands of small files (typically 1-100KB each) across Windows UNC shares, you face significant overhead from:

• File system metadata operations (create/open/close timestamps)
• NTFS permission checks
• SMB protocol negotiation per file

Using PowerShell, we can measure the performance gap:

# Test transferring 10,000 small files (5KB each)
Measure-Command { Copy-Item .\small_files\* \\target\share -Recurse }

# Test transferring single 50MB archive
Measure-Command { Copy-Item .\archive.7z \\target\share }

Typical results show archive transfers completing 3-8x faster due to:

• Single SMB session establishment
• Eliminated file system overhead
• Better network buffer utilization

For maximum throughput with 7-Zip:

7z a -t7z -mx1 -mmt=on archive.7z source_folder

Where:

• -mx1 uses fastest compression (prioritizing speed over ratio)
• -mmt=on enables multithreading
• Consider -m0=Copy for no compression if CPU is bottleneck

When archives aren't feasible:

# Robocopy with multi-threading
robocopy source dest /MT:16 /NP /R:1 /W:1

# Tar for streaming (Windows 10+)
tar -cf - . | tar -xf - -C \\target\share

NTFS performance degrades with:

• Directory entries exceeding 100,000 files
• Fragmented Master File Table (MFT)
• Antivirus real-time scanning

For massive transfers (>1M files), consider splitting archives into batches of 50,000 files.

When transferring thousands of small files (typically 1-10KB each) across Windows UNC shares, we face inherent inefficiencies in the SMB protocol. Each file transfer requires:

• New connection establishment
• Metadata operations (permissions checking, timestamps)
• Disk seek operations on both ends

Benchmark tests show that transferring 10,000 x 5KB files takes 3-5x longer than transferring a single 50MB archive containing the same data. Here's why:

// Theoretical transfer times (100Mbps network)
Small files: 
  10,000 files * (20ms overhead + 0.4ms transfer) ≈ 204 seconds

Zipped archive:
  1 file * (20ms overhead + 400ms transfer) ≈ 420ms

For programmatic solutions, consider these approaches:

Option 1: Simple PowerShell Zipping

# Compress files
Compress-Archive -Path "\\source\share\*" -DestinationPath "\\target\share\archive.zip" -CompressionLevel Fastest

# Decompress (if needed)
Expand-Archive -Path "\\target\share\archive.zip" -DestinationPath "\\target\share\extracted"

Option 2: Robocopy for Direct Transfer

robocopy \\source\share \\target\share /MIR /ZB /R:1 /W:1 /MT:16 /LOG:transfer.log
# /MT enables multithreading (16 threads in this case)

For mission-critical transfers:

• SMB Direct: Enable RDMA if supported by NICs
• Disable SMB1: Ensure SMB 3.1.1 is active
• File System Cache: Increase the cache for small files

Consider direct transfer when:

• Files require immediate random access
• Processing pipeline expects individual files
• Total transfer size is below 10,000 files