Impossible to Complete a File Copy on Any Drives

Status 2013-01-19: extant in OS X 10.8.2, probably also in 10.7.x

Attempt after attempt, the Finder kept reporting the .DS_Store error shown below (it’s a Mac OS X hidden file created by the Finder). Each time, the Finder copy would abort, and there is of course no report on how many files were copied (great way to lose data, thank you Apple).

After about a *dozen* such failures, I gave up. All I wanted to do was to copy some folders to my main system via file sharing! Except that the problem is not limited to file sharing.

The .DS_Store already exists message

In this particular case, I ended up sharing the files on the source machine, then copying them to my main machine the other direction (“pull” instead of “push”).

But it’s not just about file sharing over the network: it happens on local copies also. So the bottom line is that basic, key, core functionality is often unusable. Most of the time file copying works fine. But sometimes it repeatedly fails. I’ve had to do large copies piece-by-piece at times in order to work around the problem.

Maybe Apple should make basic operations work properly instead of implementing dilettante eye-candy progress bars on file icons.

Up to 1527MB/s sustained performance

Working theory

My working theory is that there is an internal threading bug inside the Finder: on a 12-core Mac Pro the chances of a thread-safety bug popping up are increased over that of a dual-core or quad-core machine.

For example, there might be one thread doing a file copy and another that creates the .DS_Store file for other (non copy related) reasons. Or there might be more than one copy thread. Or a create and copy thread, etc. A copy thread would be confused by finding an already existing file that it was tasked to create. Or there might be another system process or Finder helper process that also creates the .DS_Store file.

Not just networking issue

Apple knowledge base article HT1629 explains how to disable .DS_Store. In short, turn off the ugly behavior. In Terminal:

defaults write com.apple.desktopservices DSDontWriteNetworkStores true

If only it were a networking-only issue, but it is not. I have repeatedly had difficulty doing local file copies.

The folders I wanted to copy