If for some reason you need to move your cache from one drive to another on your server (if you have multiple servers, it's the one with the filecache), then please read the guide on "Adding drives for cache" as files used in here are referenced.
NOTE: This is best done outside normal work hours, as you will have to restart the filecache's app pool a couple of times and this may cause clients uploads to restart.
1. Ensure that your new destination is added to your ArchiveDrives.cfg (mentioned in the guide above).
(Note: remember to restart the filecache's App pool to load in the new destinations.)
2. Preferably, you should stop the filecache's app pool in the IIS now to stop any new files from being uploaded.
(Note: this will mean people won't be able to download files either.)
3. Then copy the files from your old destination to your new destination.
4. Afterwards, remove the old location from the ArchiveDrives.cfg and (re)start the filecache's app pool again.
(Note: please ensure in the logs that the new destination was correct.)
5. Only if you weren't able to stop the filecache while the above steps.
Copy all files from the old location to the new location again.
6.Now all the files will be downloaded from the new location instead.
And all new files will be placed here as well.
7. If possible, test it by downloading a file from one of the companies whose data was moved.