I've got an old win 2003 VM (VMware) on a blade cluster of VMs that I'm moving a considerable amount of files to our new DFS array. There are two main folders with about 1.7 million and half a million smaller files (letters, memos, and other smaller files) respectively. Total size is ~420 GB and ~100 GB.

We're using the gui version of robocopy on the server to copy the files. We had initiated a file copy about a month ago to test the process and found that it was taking around 4 hours for the large file. Now that I'm in the process of actually switching the files over it has been taking 18-20 hours. Nothing has changed on the server side and nothing has changed on the settings of the copy (no logs, 1 retry with a wait of 1 second).

Our intent is to shut off the share and force the copy over again to get all the files that have been left out of the copy due to being locked by users. I can't take a 20 hour outage to do that though.

Does anyone have any theories about what could be causing such a delay for robocopy compared to previously shorter runs?