Robocopy bug with /b switch

Question

Robocopy without /b is able to copy files which are currently open (e.g. a Word document open in Word).
Robocopy with /b is not able to copy these same files.
Steps to reproduce:
Prerequisites:
your user account is an administrator (in a domain, you are in Domain Admins).
your user account is in the "Backup Operators" group.
you have logged off and back on since adding yourself to Backup Operators.
Create a folder called 'source'.
In 'source', create a Word document called 'file.docx'.
Open 'file.docx' in Word.
Run Powershell as administrator and cd to the directory in which you created 'source'.
robocopy /mir source\ dest_without_b\
robocopy /mir source\ dest_with_b\ /b
Expected result:
Steps 5 and 6 both complete without error, and target folders "dest_without_b" and "dest_with_b" now contain "file.docx" and "~$file.docx" (Word's "I have this file open" file).
Actual result:
Step 5 succeeds, but step 6 fails with this error:
2014/08/27 10:36:58 ERROR 32 (0x00000020) Copying File G:\scratch\source\file.docx
The process cannot access the file because it is being used by another process.
Waiting 30 seconds...
Notes:
This bug is present in at least Windows 8, 8.1, 7, and Server 2008 R2.
This bug happens regardless of whether source\file.docx is a local file or on a network share, and regardless of whether file.docx is open on the local machine or the remote machine.
This means that when backing up a workstation where someone is currently logged on, I need to choose between getting files which the user has open, and getting files which my user account does not have permission to. I can run robocopy twice, once with
/b and once without, and hope that I get everything -- but I will not get files which are both in use
and not readable to my user account.
There are at least two different kinds of "file open" in Windows: Microsoft Word's "I have this file open but I'll still let you copy it" mode, and the "You are never copying this file while the computer is running, unless you use
Volume Shadow Copy" mode used by the Windows registry. Robocopy cannot copy files in the latter case, with or without /b (but it would be really nice if it could).
Finally, I'm new to reporting bugs in Windows / Microsoft products. Is there a public bugzilla / bug tracker or something?

Answer 1

Hi,
Robocopy doesnt copy open files. The defaults allow 1 million retries, at 30-second intervals, allowing copy
operations to complete when an open file is closed, even if hours or days have passed since the command was first launched.
Thus, please run robocopy /mir source\ dest_with_b\ /b after you restart the computer to check the result.
Karen Hu
TechNet Community Support