Python 2.7及XCOPY复制本地到网络存储G-Code文件不完整问题

Let's break down why your 103KB G-Code TXT file keeps truncating at line 6285 (mid-way through "Z17.168 Y7.393" to "Z17.168 Y7.3") and how to fix it. This consistent truncation at the exact spot points to a predictable issue, not random network flakiness.

Possible Root Causes #

• Network Storage Cache/Flush Delay: Many network drives use write caching to boost performance. If the system assumes the copy is complete before the cache finishes writing to disk, you'll end up with a truncated file.
• Hidden File Anomalies: A non-ASCII control character or malformed line ending near line 6285 might be causing the write operation to abort prematurely.
• Limitations of Basic Copy Tools: XCOPY and naive Python file copies often don't handle network storage quirks (like partial writes) as reliably as purpose-built tools.

Step-by-Step Fixes #

1. Verify the Source File is Intact #

First, rule out a corrupted source file:

• Copy the file to a local folder (not network storage) using:

  copy "C:\path\to\source.txt" "C:\temp\test.txt"
  

• Compare the two files with a binary check to ensure they match:

  fc /B "C:\path\to\source.txt" "C:\temp\test.txt"
  

• Alternatively, verify MD5 hashes to confirm integrity:

  certutil -hashfile "C:\path\to\source.txt" MD5
  certutil -hashfile "C:\temp\test.txt" MD5
  

If the checks pass, the source file is fine—your problem lies with the network storage.

2. Use Robocopy Instead of XCOPY #

Robocopy is designed for reliable network transfers. Try this command:

robocopy "C:\source\folder" "\\network\drive\folder" "your-file.txt" /Z /R:3 /W:5

• /Z: Enables restartable mode to resume interrupted transfers
• /R:3: Retries 3 times if a write fails
• /W:5: Waits 5 seconds between retries

3. Fix Your Python Copy Code #

If you prefer using Python, add explicit buffer flushing and disk sync to ensure all data is written to the network drive. For Python 2.7, use this modified function:

import os

def safe_copy(src_path, dst_path):
    buffer_size = 1024 * 1024  # Use 1MB chunks for efficient transfer
    with open(src_path, 'rb') as src_file:
        with open(dst_path, 'wb') as dst_file:
            while True:
                chunk = src_file.read(buffer_size)
                if not chunk:
                    break
                dst_file.write(chunk)
                dst_file.flush()  # Push data from OS buffer to network drive
                os.fsync(dst_file.fileno())  # Force network drive to write to disk

4. Check for Hidden Characters in the Source File #

Open your G-Code file in Notepad++ (enable "Show All Characters" via View > Show Symbol > Show All Characters) and inspect line 6285 and nearby lines. Look for:

• Non-printable control characters (like ^@ or other odd symbols)
• Malformed line endings (e.g., only LF instead of CRLF)
  If you find any anomalies, clean up the line and try copying again.

5. Wait for Cache Flush After Copy #

After any copy operation, don't immediately disconnect the network drive or close the terminal. Wait 1-2 minutes to give the network storage time to write cached data to disk. Some drives have a LED indicator that stops blinking when writes are complete—wait for that signal.

6. Check Network Storage Health & Settings #

• Ensure the network drive has enough free space (even small files need room for temporary writes)
• If using SMB, try upgrading to SMB 3.0 (Windows: Control Panel > Network and Sharing Center > Change advanced sharing settings > Enable SMB 3.0)
• Confirm the network storage has no unexpected file size limits (unlikely for 103KB, but worth checking)

内容的提问来源于stack exchange，提问作者m0h