## 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 introduced as a standard feature of Windows VistaWindows 7 and Windows Server 2008. The command is literally robocopy.

## Features

Robocopy is notable 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 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 only) [2]
• Return code[3] on program termination for batch file usage.

Notably, Robocopy will fail to copy open files. The so-called Backup mode is sometimes mistaken as an ability to copy open files, which it is not. Backup mode is an administrative privilege that allows Robocopy to override permissions settings (specifically, NTFS ACLs) for the purpose of making backups. The Windows Volume Shadow Copy service is the only Windows subsystem that can copy open files, which it does by snapshotting them for point-in-time consistency. Robocopy does not implement accessing the Volume Shadow Copy service in any way, inhibiting its usefulness as a backup utility for volumes that may be in use. However, one can use separate utilities such as VSHADOW or DISKSHADOW (included withWindows Server 2008) to create a shadow copy of a given volume which Robocopy can back up.

On the other hand, by design, the original Robocopy version is not able to replicate security attributes of files which have had their security permissions changed after an initial mirroring.[4] This behavior was changed on Robocopy versions included in Windows 2008 and Windows Vista. The downside of this is that Robocopy does not behave consistently between platforms.[5]

## 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), and 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 restartable mode (/Z) in case network connection is lost:

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

It should be noted that using the /Z switch results in marked slowdown of copy operations.

## 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 utilized in a session. In theory, the following formula expresses the delay (D, in milliseconds) required to simulate a desired bandwidth (BD, in kilobits per second), over a network link with an available bandwidth of BA 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 utilized by Windows Update and BranchCache).

Email notification of Robocopy jobs success or failure can be established using a utility called RoboCopyPlus (see link below). An extension to Robocopy it enables it to send email notifications based on ‘Success’, ‘Warning’ or ‘Error’ result of the Robocopy job. It can condense logfiles to show warnings and error only, and optionally attaches these to the email message based on level of success, warning or error. The product works with any version of Robocopy, as it acts as a ‘wrapper’ around it. Existing configurations using Robocopy, often called from scheduled batch files, do not need to be altered, other then by replacing ‘Robocopy’ with ‘RoboCopyPlus’ and adding the parameters to configure email notification and/or report condensing.

## Windows event logging

RoboCopyPlus (see link below) enables Robocopy to write log entries in the Windows event log (application log). It forwards the exit codes of the Robocopy job to the log and the log-type (‘informational’, ‘warning’, ‘Error’) represents the Robocopy job result. This feature enables Robocopy to be used in environments where network management based on event log scanning is used, as is common for many larger organisations and ICT solution providers.

## 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.[6] The Microsoft Robocopy GUI also includes version XP026 of Robocopy (Vista version). When downloaded from the TechNet link below, the version reported is “Microsoft Robocopy GUI 3.1.2.”

There are other non-Microsoft GUIs for Robocopy. The most popular among them appears to be a program by SH-Soft, confusingly also called “Robocopy GUI” [7]. Another one is called “WinRoboCopy”. [8]

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. [9]

## Versions

Product version File version Year Origin Other
1.70 1997 Windows NT Resource Kit
1.71 4.0.1.71 1997 Windows NT Resource Kit
1.95 4.0.1.95 1999 Windows 2000 Resource Kit
1.96 4.0.1.96 1999 Windows 2000 Resource Kit (c) 1995-1997
XP010 5.1.1.1010 2003 Windows 2003 Resource Kit
XP027 5.1.10.1027 2008 Bundled with Windows Vista, Server 2008 and later (c) 1995-2004

## References

1. ^ http://windowsitpro.com/Windows/Articles/ArticleID/44324/pg/2/2.html Robocopy XP010 FAQ Wield powerful new switch options.
2. ^ http://technet.microsoft.com/en-us/magazine/dd542631.aspx
3. ^ http://support.microsoft.com/kb/954404/en-us Robocopy Return Codes
4. ^ Microsoft’s Robocopy compromise.
5. ^ Ugly bug in Robocopy – ignoring security on file level.
6. ^ “Utility Spotlight Robocopy GUI”TechNet Magazine (Microsoft Corporation and CMP Media, LLC). November, 2006. Retrieved 2008-07-17.
7. ^ http://www.sh-soft.com/front_content.php?idcat=7 SH-Soft Tools: Robocopy GUI
8. ^ http://www.upway2late.com/projects/winrobocopy WinRoboCopy, a GUI front end for RoboCopy.
9. ^ “Free Utility: RichCopy, an Advanced Alternative to RoboCopy”TechNet Magazine (Microsoft Corporation and CMP Media, LLC). November, 2006. Retrieved 2008-07-17.