Use robocopy to mirror source but ignore timestamp

3

I want to backup a folder to a share on a linux nas with robocopy.

I use the commandline robocopy /mir <source> <dest>

After a succesfull copy in explorer the timestamps are equal but somehow robocopy copies the same file the next time it runs and claims source file is newer. Seems to be a problem with the smb version on the nas.

Now I can use /xn switch to prevent the file copy but that will also prevent the file from being copied the next time I run the same job.

So my question is: How do I use robocopy to ignore the timestamp but only copy a file if the file size changed (I know this would not be a 100% solution) but since I want to backup office documents and pictures, this would be OK for me.

Jürgen Steinblock

Posted 2016-01-14T07:49:37.430

Reputation: 318

You already know this idea has issues - content can change without affecting file size. Also, the modified date can be altered by things like AV. I wrote a back up program (to back up my Windows files to my Linux NAS too) because I ran into these problems using XCOPY and Robocopy. You are better to get the HASH of the file and then compare them but this isn't do-able in robocopy. Since robocopy isn't the right tool (IMO), why not use other software? What actually is the issue? If you're only copying office documents and pictures, I assume the time it takes isn't really a problem? – Dave – 2016-01-14T08:14:48.077

Answers

3

After a succesfull copy in explorer the timestamps are equal but somehow Robocopy copies the same file the next time it runs and claims source file is newer. Seems to be a problem with the smb version on the nas.

Add the /FFT switch with Robocopy:

ROBOCOPY /MIR /FFT <source> <dest>

Robocopy Switch

/FFT : Assume FAT File Times (2-second date/time granularity).

Better Description

/FFT uses fat file timing instead of NTFS. This means the granularity is a > bit less precise. For across-network share operations this seems to be much more reliable - just don't rely on the file timings to be completely precise to the second.

Pimp Juice IT

Posted 2016-01-14T07:49:37.430

Reputation: 29 425

1That did the trick. Thumbs up – Jürgen Steinblock – 2016-01-14T08:37:20.687

Asked: 2016-01-14T07:49:37.430

Viewed: 3 308 times

Active: 2016-01-14T14:01:40.887