Selfhosted

I don't know if this is naughty but I use bind mounts for everything, and docker compose to keep it all together.

You can map directories or even individual files to directories/files on the host computer.

Normally I make a directory for the service then map all volumes inside a ./data directory or something like that. But you could easily bind to different directories. For example for photoprism I mount my photos from a data drive for it to access, mount the main data/database to a directory that gets backed up, and mount the cache to a directory that doesn't get backed up.

If you use a volume, you can mount that anywhere.

volumes:
  lemmy_pgsql:
    driver: local
    driver_opts:
      type: none
      o: bind
      device: '/mnt/data/lemmy/pgsql'

Then in your service add a volume

    volumes:
      - lemmy_pgsql:/var/lib/postgresql/data:Z

No idea. I personally use PVs and PVCs with k3s and it's trivial there with some downtime

You can run docker containers with multiple volumes. e.g. pass something like -v src1:dst1 -v src2:dst2 as arguments to docker run.

So -- if I understood your question correctly -- yes, you can do that.

I have several NFS shares that host multiple docker volumes. So yes.

This is mostly an IOPS dependent answer. Do you have multiple hot services constantly hitting the disk? If so, it can be advantageous to split the heavy hitters across different disk controllers, so in high redundancy situations that means different dedicated pools. If it’s a bunch of services just reading, filesystems like ZFS use caching to almost completely eliminate disk thrashing.