The case I have is a directory that stores phone call recordings throughout the day. The root filesystem is running out of space so we added an external hard drive. This server may not be taken out of production for any reason, so what I would like to do is mount the new disk over the same recordings directory, and then after all of the calls in progress have finished I would copy them from the old filesystem into the new one.
I will be able to determine when the calls in progress during this transition have been finished up.
My question is how can I access the files beneath /var/x/y/recordings/ after I mount a new disk onto /var/x/y/recordings/?
I believe an open file should be able to finish being written to and eventually closed after a new FS is mounted over its parent directory. Is this incorrect?