Hello Sonia,

Thank you for reaching out, and I am happy to help!
You are correct, the Disk method is not recommended for DB aching in W3 Total Cache. What is recommended to use for DB Caching and Object Caching is a memory-based caching method like Redis or Memcached.
Now, depending on the server, you may already have that available so please check with yoru hosting provider if they can install PHP Redis and enable it for you
If you are on a shared server, however, it’s recommended not to use Disk caching method to avoid issues and potentially filling up the disk space

Thanks!