When you run e-sync then it creates temporary copies of files in the windows temp directory before it actually commits them to actual location. If E-Sync fails then these files are not cleaned up and they stay in windows/temp directory itself. As ESync is using underlying windows sync service, this directory can not be re-configured to some other data drive. Sometime this can cause serious issues on production environment because it will keep on dumping files in C:\Windows\Temp directory and this can make your C:\ drive full silently.
To avoid any future production problems, I suggest to have a clean up program running on your source and target machines which cleans up these temp files on regular basis. It will be good to take a snapshot of the directory as well and move to your data back up drive and send out some emails to support team so that they can analyse the E-Sync failures.
This is a simple thing to perform before your application goes to production but debugging these issues when system is live can cause lots of pains!
