When transferring 20TB between Windows Server 2012 R2 systems, the performance gap between Robocopy and Explorer drag-and-drop is staggering. While Explorer achieves expected gigabit speeds (110MB/s), Robocopy crawls at 5-10MB/s despite identical network conditions.

The original command demonstrates proper syntax:

robocopy /S /ZB /MOVE /J /DCOPY:A /V /FP \\oldserver\shared\folder X:\folder

Yet it underperforms significantly compared to manual file operations.

Several elements contribute to this performance discrepancy:

• Buffering differences: Explorer uses larger I/O buffers by default
• Metadata handling: Robocopy performs more comprehensive attribute copying
• Thread management: Default single-threaded operation vs Explorer's concurrent transfers

This optimized command achieves near-Explorer speeds:

robocopy /S /ZB /MT:16 /R:1 /W:1 /NP /NFL /NDL /DCOPY:A \\source\share X:\target

Key improvements:

• /MT:16: Enables multi-threading (16 workers)
• /R:1 /W:1: Reduces retry delays
• /NP /NFL /NDL: Minimizes console output overhead

For massive transfers where Robocopy still underperforms:

# PowerShell alternative (Windows Server 2012 R2+)
Start-BitsTransfer -Source \\server\share -Destination X:\target -Priority High -TransferType Upload

To confirm transfer speeds:

# Real-time throughput monitoring
Get-Counter '\Network Interface(*)\Bytes Total/sec' -Continuous

NTFS vs ReFS performance characteristics:

• NTFS generally handles small files better
• ReFS shines with large sequential writes
• Consider disabling last access timestamp updates: fsutil behavior set disablelastaccess 1

When migrating massive datasets (20TB in this case) between Windows Server 2012 R2 systems, the performance difference between Robocopy and Explorer's drag-and-drop is staggering. While Explorer achieves the expected 110MB/s (near gigabit saturation), Robocopy crawls at 5-10MB/s with these parameters:

robocopy /S /ZB /MOVE /J /DCOPY:A /V /FP \\oldserver\shared\folder X:\folder

• Direct Ethernet connection between servers showed no improvement
• Multithreading (/MT 1-16) had negligible impact
• Copy vs move operations performed equally poorly
• Output redirection to log files didn't help
• Push vs pull methodology made no difference

The primary suspects in such cases are typically:

1. Small file syndrome (numerous tiny files causing metadata overhead)
2. Excessive verification switches (/V /FP)
3. Journaling requirements (/J)
4. Buffering issues with /ZB (restartable mode backup semantics)
5. Filesystem ACL inheritance processing

For maximum throughput with large datasets, try this alternative approach:

robocopy \\source\share X:\destination /MIR /ZB /MT:32 /R:1 /W:1 /NP /TEE /XD "$RECYCLE.BIN" "System Volume Information"

Key improvements:

• /MT:32 enables maximum parallelization (adjust based on CPU cores)
• /R:1 /W:1 reduces retry delays
• Exclusion of system directories reduces unnecessary operations
• /NP eliminates percentage calculations that impact performance

When Robocopy won't cooperate, consider these PowerShell alternatives:

# Method 1: Simple Copy-Item with buffering
$source = "\\oldserver\shared\folder"
$dest = "X:\folder"
Get-ChildItem -Path $source -Recurse | Copy-Item -Destination {
    Join-Path $dest $_.FullName.Substring($source.length)
} -Force

# Method 2: Bit-Transmitter using .NET
$srcStream = [System.IO.File]::OpenRead("\\oldserver\file.dat")
$dstStream = [System.IO.File]::Create("X:\folder\file.dat")
$buffer = New-Object byte[] 8MB
while (($read = $srcStream.Read($buffer, 0, $buffer.Length)) -gt 0) {
    $dstStream.Write($buffer, 0, $read)
}

For NTFS to NTFS transfers, consider:

• Disabling last access timestamp updates (fsutil behavior set disablelastaccess 1)
• Increasing the NTFS MFT zone reservation
• Verifying cluster sizes match between source and destination

If you absolutely must maintain Explorer-like speeds but need Robocopy's reliability, consider this hybrid approach:

# Phase 1: Bulk transfer with Explorer
xcopy \\oldserver\shared\folder X:\folder /E /H /C /K /Y /J

# Phase 2: Robocopy verification pass
robocopy \\oldserver\shared\folder X:\folder /L /MIR /NS /NC /NFL /NDL /NP