hello,
the vfs dir cache uses ram and is always required.
have a read of my comparison of the vfs dir cache and the vfs file cache
https://forum.rclone.org/t/status-about-using-rclone-for-music-storage-playback-in-2021-access-times-improved/27648/34
as far as i know, that is not possible, the buffer is not persistent.
see this open issue
https://github.com/rclone/rclone/issues/5592
you can use the vfs file cache and store that in the ramdisk.
note, that --vfs-cache-max-size is a soft limit and possible for rclone to use more space.
and if a file is open/locked/in-use, rclone will not remove it.
and for my mounts, when streaming from cloud, i use
--- --read-only
--- do not use --vfs-cache-mode, in effect --vfs-cache-mode=off