This was an idea I had while working on the PCH project and discovering that pch obj files are much larger and there fore slow down the cache due to increased transfer speed. The effects of this idea would be useful even outside of the context of PCH. This would be a special mode, intended for use in evergreen where we transfer a large amount of data over network from the scons cache EFS.

The idea would be to make the cache use a symlink when copying from the cache instead of actually copying the file. There are probably some other places we will need to examine that are able to use the symlinks correctly, for example:

• Does hardlink install action still work correctly?
• Do packaging scripts work with these symlinked files?
• To make sure the symlinked file doesn't drop out from under us while we are linked, we will need to make a hardlink inside the EFS, and symlink to that instead, and then delete the hardlink after the evergreen build is done?