How to move index folder to a different drive

Hi, I have installed Plex on an SSD 32GB small drive where my Linux Mint is residing. Now with indexing a lot of movies which are on a HDD, my index file and caches residing on 32Gb drive fills in the drive pretty quickly. I need to move out the indexing / caching folders into a different HDD, but I cannot see any options in the Plex Server for that.
Is there a way to do so?
I tried to search internet and modified Plex Config file and even created symbolic link and moved the folder to HDD. But Plex does not use it and just recreated a cach / index folder in the same place on my 32Gb ssd.
Please advise.
Dmitry