Robocopy puzzle

I use Robocopy to create a backup of a folder structure - 3469 files in 285 folders. I run it every few months. A handful of files get added or deleted but it's basically very static. The command (in a script) is "RoboCopy %Source% %Dest% /mir /dcopy:T". Since there are few changes usually very few files get copied but today almost every file got flagged "Newer" and got copied:



(I couldn't find the 2 that got skipped, but I didn't look very hard.)

In order to debug this I restored the whole destination volume and ran a WinMerge compare of the source and destination. It found no differences so I randthe Robocopy again with the same results - all but 2 files were copied. I have no idea how either WinMerge or Robocopy do their comparisons but I believe there were no additions or deletions of files since I did the last copy so I think I believe WinMerge in this case.

Does Robocopy look at the "Last accessed" date? The source is on a flash drive and my antiviral product - BitDefender - did a scan of the device when I plugged it in.
The last time I did a copy was last year. Would that have any effect?

This mostly just curiosity on my part.

Robocopy will consider a file changed if the file size or timestamp is different, unless you fiddle with parameters to change that. You might be triggering by using DCOPY:T.

You can specify how WinMerge compares directories by using the Options button when you start the comparison. Changing to date, size, or both might help you narrow down which is triggering your re-copy.

View attachment 121803

I think the DCOPY parm controls Robocopy's detection of directory changes, and the directory comparisons seemed fine.

I ran a WinMerge comparison again (comparing full content) - this time between a source from a Macrium Reflect backup of the destination (taken this morning) and the source on the flash drive. Once again all content was judged identical, but right and left "dates" were off by exactly one hour. That explains Robocopy copying everything, but I can't explain the timestamp differences (but I bet daylight savings time is involved somehow).

And I found a problem in my Robocpy commands. This was actually a two-step process" export from a laptop to a flash drive, and import from the flash drive to my PC. The export Robocopy had /XO in addition to the parms I showed earlier ... and the problematic time differences exist between the laptop and flash drive. I think I need the /XO everywhere. (But I don't know if that will fix the problem.)

The flash drive could be the issue if it’s not NTFS.

Anyhoo…. Robocopy has a DST switch for times like this (pun intended).

Also this sounds like an excellent case for using git or some other source control.

Hmm. I hadn't noticed the DST switch. It isn't very well documented. I'll play with it to see how it works.

I think git is far beyond my needs. These are just some simple scripts used to get data to and from several off-line laptops.

I meant git for the data, not the scripts.

I know nothing about git so I may be way off base here, but I don't think it makes much sense for my purposes. I have a set of data and config files for an application running on a couple laptops. The laptops are off-line except for the rare occasions when I take them home to apply maintenance (and once Win10 goes out of support they will remain off-line always). I use robocopy scripts to move data between the laptops and a flash drive and between the flash drive and my desktop. On the desktop I have another copy of the application and the data and config files.

I could use git (or something similar) as a repository for the data, but I would still need a working copy of the data (not a git repository) on the PC and would still need to get data to and from the off-line laptops.

Thanks, but I have it working now. The /DST and /XO fixed my problem. I didn't walk through your script so I'm not sure if understand what you're doing, but it looks more complex than I need.

pokeefe0001 said:

Thanks, but I have it working now. The /DST and /XO fixed my problem. I didn't walk through your script so I'm not sure if understand what you're doing, but it looks more complex than I need.

Click to expand...

It opens file explorer for you to select source and target folders and creates a full or incremental backup of the source files to target folder, it only copies changed and missing files to target folder.


You can change the Robocopy /E /IM /FP command at the bottom of the script with your command.

FreeBooter said:

It opens file explorer for you to select source and target folders and creates a full or incremental backup of the source files to target folder, it only copies changed and missing files to target folder.

Click to expand...

I thought that might be what it did when you mentioned "incremental backup". I'm not creating backups; I'm creating a working copy of the original source ... including additions, changes, and deletions. Having incremental changes in a separate folder would do me no good.