After restoring a file share from backup, I discovered some files were corrupt while users continued modifying other files. The challenge: overwrite all files from backup except those that users have modified (newer timestamp).

The solution lies in using robocopy's time comparison flags. The /XN (exclude newer) switch is key:

robocopy "\\backup\share" "\\production\share" /E /COPYALL /XN /XO /R:3 /W:5 /LOG:C:\robocopy.log

• /XN - Exclude files newer than source (protects user modifications)
• /XO - Exclude older files (though redundant with /XN in this case)
• /COPYALL - Copy all file info (timestamps, attributes, etc.)
• /E - Copy subdirectories including empty ones

Imagine this directory structure before running robocopy:

Backup:
File1.txt (2023-01-01)
File2.txt (2023-01-01)

Production:
File1.txt (2023-01-01) [corrupt]
File2.txt (2023-01-05) [user modified]

The command would:

• Overwrite File1.txt (same timestamp in backup)
• Skip File2.txt (newer in production)

While you mentioned /IS, note it includes same files (doesn't exclude newer). For completeness:

robocopy source dest *.* /IS /XN

This would still protect newer files while including identical files (which might be necessary in some scenarios).

Always include logging for verification:

/LOG+:C:\robocopy.log /TEE /NP /NDL

The /LOG+ appends to existing logs, while /TEE outputs to both console and log file.

For network shares with intermittent connectivity issues:

/R:5 /W:10 /REG /MIR /ZB

This adds retry logic (5 attempts waiting 10 seconds between), registry-based restart capability, and mirror mode with backup mode.

When dealing with file synchronization after a backup restoration, we often encounter scenarios where:

Some restored files might be corrupted while backups remain intact
Users continue modifying files during the recovery process
We need to selectively overwrite files without losing recent changes

The key to solving this lies in Robocopy's timestamp comparison capabilities. The /XO (eXclude Older) switch is particularly useful:
robocopy source destination /XO /COPYALL /E /R:1 /W:1
This command will copy files from source to destination, excluding files where the destination is newer.


Switch
Description


/XO
Exclude older files (skip if destination is newer)


/XN
Exclude newer files (opposite of what we want)


/XX
Exclude extra files (not relevant here)


/IS
Include same files (overwrites identical files)


For a complete solution that handles permissions and retries:
robocopy \\server\share\source \\server\share\destination /MIR /XO /COPY:DATSOU /DCOPY:T /R:3 /W:5 /LOG:C:\robocopy.log /TEE
Breaking this down:

/MIR - Mirror mode (careful with this in production)
/COPY:DATSOU - Copy all attributes including security
/DCOPY:T - Copy directory timestamps
/R:3 - Retry 3 times
/W:5 - Wait 5 seconds between retries
/LOG - Create output log
/TEE - Output to console and log

For more granular control, consider this PowerShell script:


$source = "C:\source"

$dest = "C:\destination"

Get-ChildItem $source -Recurse | ForEach-Object {

    $destFile = Join-Path $dest $_.FullName.Substring($source.Length)

    if (Test-Path $destFile) {

        if ($_.LastWriteTime -gt (Get-Item $destFile).LastWriteTime) {

            Copy-Item $_.FullName -Destination $destFile -Force

        }

    }

    else {

        Copy-Item $_.FullName -Destination $destFile -Force

    }

}


Always test with /L (list-only) mode first:
robocopy source destination /XO /L /NP /LOG:C:\test.log
This will show what would be copied without actually making changes.

Using /MIR without /XO will delete newer files in destination
Not using /COPYALL might miss security attributes
Forgetting /R and /W could cause failures on busy networks
Missing /TEE makes monitoring progress difficult