Robocopy

Robocopy, or "Robust File Copy", is a command-line directory replication command. It has been available as part of the Windows Resource Kit starting with Windows NT 4.0, and was first introduced as a standard feature in Windows Vista and Windows Server 2008. The command is robocopy.

Features

Robocopy is noted for capabilities above and beyond the built-in Windows copy and xcopy commands, including the following:

• Ability to tolerate network interruptions and resume copying. (incomplete files are marked with a date stamp of 1980-01-01 and contain a recovery record so Robocopy knows where to continue from)
• Ability to skip NTFS junction points which can cause copying failures because of infinite loops (/XJ)
• Ability to copy file data and attributes correctly, and to preserve original timestamps, as well as NTFS ACLs, owner information, and audit information using command line switches. (/COPYALL or /COPY:) Copying folder timestamps is also possible in later versions (/DCOPY:T).
• Ability to assert the Windows NT "backup right" (/B) so an administrator may copy an entire directory, including files denied readability to the administrator.
• Persistence by default, with a programmable number of automatic retries if a file cannot be opened.
• A "mirror" mode, which keeps trees in sync by optionally deleting files out of the destination that are no longer present in the source.
• Ability to skip files that already appear in the destination folder with identical size and timestamp.
• A continuously updated command-line progress indicator.
• Ability to copy file and folder names exceeding 256 characters — up to a theoretical limit of 32,000 characters — without errors.^[1]
• Multithreaded copying. (Windows 7 and Windows Server 2008 R2) ^[2]
• Return code^[3] on program termination for batch file usage.

Limitations

No open files

Robocopy will not copy open files. Any process may open files for exclusive read access by withholding the FILE_SHARE_READ^[4] flag during opening. Even robocopy's Backup mode will not touch those files. (Backup mode instead runs Robocopy as a "Backup Operator". This allows Robocopy to override permissions settings (specifically, NTFS ACLs).^{[5] [6]})

The Windows Volume Shadow Copy service is used for such situations, but Robocopy does not use it. Therefore Robocopy is not useful for backing up live operating system volumes. However, one can use a separate utility, such as DiskShadow.exe^[7] (included with Windows Server 2008), to create a shadow copy of a given volume, which Robocopy can then be directed to back up. A similar utility that works like Robocopy that has the option to copy open files is GSCopyPro.

XP mirroring bug

Robocopy versions on systems older than Windows Vista do not mirror properly. They ignore changed security attributes of previously mirrored files.^{[8] [9]}

Wildcarding treatment

The /XF switch does not work if given both a directory and a wildcard. For example /XF pictures\*.jpg generates an error.

Common usage scenarios

• Copy directory contents of A to B (including file data, attributes and timestamps), recursively with empty directories (/E):

Robocopy C:\A C:\B /E

• Copy directory recursively (/E), copy all file information (/COPYALL, equivalent to /COPY:DATSOU, D=Data, A=Attributes, T=Timestamps, S=Security=NTFS ACLs, O=Owner info, U=aUditing info), do not retry locked files (/R:0)(the number of retries on failed copies default value is 1 million), preserve original directories' Timestamps (/DCOPY:T - requires version XP026 or later):

Robocopy C:\A C:\B /COPYALL /E /R:0 /DCOPY:T

• Mirror A to B, destroying any files in B that are not present in A (/MIR), copy files in resume mode (/Z) in case network connection is lost:

Robocopy C:\A \backupserver\B /MIR /Z

For the full reference, see the Microsoft TechNet Robocopy page.^[10]

Folder copier, not file copier

Robocopy syntax is markedly different from standard copy commands, as it accepts only folder names as its source and destination arguments. File names and wild-card characters (such as "*.*") are not valid source or destination arguments. Files may be selected or excluded using the optional filespec filtering argument. Filespecs can only refer to the filenames relative to the folders already selected for copying. Fully qualified path names are not supported.

For example, in order to copy the file foo.txt from directory c:\bar to c:\baz, one could use the following syntax:

 Robocopy c:\bar c:\baz foo.txt

Bandwidth throttling

Robocopy's "inter-packet gap" (IPG) option allows some control over the network bandwidth used in a session. In theory, the following formula expresses the delay (D, in milliseconds) required to simulate a desired bandwidth (B_D, in kilobits per second), over a network link with an available bandwidth of B_A kbps:

In practice however, some experimentation is usually required to find a suitable delay, due to factors such as the nature and volume of other traffic on the network. The methodology employed by the IPG option may not offer the same level of control provided by some other bandwidth throttling technologies, such as BITS (which is used by Windows Update and BranchCache).

GUI front-end

Although Robocopy itself is a command-line tool, Microsoft Technet has provided a GUI front-end. The GUI requires the installation of the .NET Framework 2.0 (40 MB), if it is not already installed. It was developed by Derk Benisch, a systems engineer with the MSN Search group at Microsoft.^[11] The Microsoft Robocopy GUI also includes version XP026 of Robocopy. When downloaded from the TechNet link below, the version reported is "Microsoft Robocopy GUI 3.1.1."

There are other non-Microsoft GUIs for Robocopy:

• "WinRoboCopy" revision 1.2.4482.39775 released in April 9, 2012.^[12]
• "Easy RoboCopy" latest version 1.0.13 released in January 11, 2012.^[13]
• A program by SH-Soft, also called "Robocopy GUI" v1.0.0.24 (October 8, 2005).^[14]

A copying program with a GUI, RichCopy, is also available on Microsoft's Technet. While it is not based on Robocopy, it offers similar features, and it does not require the installation of the .NET 2.0 framework. ^[15]

Versions

See also

• Daftar/Tabel -- file copying software
• Command line
  • Daftar/Tabel -- DOS commands
  • copy (command)
  • XCOPY
  • rsync
  • GSCopyPro - Copy open files from command line
• GUI
  • SyncToy
  • RichCopy
  • Ultracopier

References

External links

• Official sources
  • Robocopy download (Version XP010) as part of Windows Server 2003 Resource Kit Tools. Includes 35-page documentation "robocopy.doc".
  • Robocopy short documentation on Microsoft TechNet Library
  • Robocopy GUI download (Version 3.1.2.0) on Microsoft TechNet Magazine
• Other
  • ROBOCOPY.exe (XP Resource Kit/Standard Vista command)
  • Robocopy.exe Robust File Copy Utility Version XP010 (35-page manual about Robocopy version code "XP010". PDF-Version of the "robocopy.doc"-file distributed with Windows Server 2003 Resource Kit Tools.)