oohhh okay I see so basically we need a something like filesystem storage as a volume.

That's correct.

When it spins back up, are we still able to mount the existing volume (in case we use filesystem volumes), then restoring/creating the memory again.

Yeah, that's fine. But Typesense will have to re-build the in-memory indices again. Depending on your index size this might take some time and won't be instantaneous. So your cold start times will be high