What are the differences in disk mounting between a virtual machine and a container?

Virtual Machine:

• Mounts block devices (e.g., virtual disks .vmdk, .vhd).
• Uses standard filesystems (XFS, Ext4, NTFS, etc.) by formatting block devices.
• Mounting occurs at the OS kernel level inside the VM, managed by the hypervisor.
• Various types of mounting are available, including RDM (Raw Device Mapping) for direct access to physical disks.

Container:

• Uses overlay filesystem concepts (AUFS, overlay2).
• Mounts image layers and overlays volumes on top of layers.
• Volume can be:
  • host path mount (mounting a directory from the host system).
  • named volume (managed by Docker daemon or orchestrator).
  • volume driver (plugins for different storage, e.g., Ceph, GlusterFS).
• Mounting is done via chroot/pivot_root mechanism and namespace in the host kernel.
• Container filesystem is formed from image layers and writable layer, onto which volumes can be mounted.
• Container filesystem is ephemeral by default, data is stored only in volumes.

Differences:

Attribute	Virtual Machine	Container
Main mechanism	Block device, Filesystem	Overlay FS, Volumes
Mount level	OS kernel inside VM, Hypervisor	Host kernel (namespace, chroot)
Storage types	Virtual disks, physical disks (RDM)	Host-path, named volumes, drivers
Filesystem durability	Depends on disk	Ephemeral (except volumes)
Formatting	Required on block device	Filesystem formed from layers and mounts

# Example of mounting in Docker Compose
volumes:
  data_volume: # Named volume
    driver: local # Or another driver
  logs_volume: # Host path mount
    type: bind
    source: /var/log/myapp
    target: /app/logs

services:
  myapp:
    image: myapp_image
    volumes:
      - data_volume:/app/data # Mounting named volume
      - logs_volume:/app/logs # Mounting host path