Final answer:
Virtual machines typically access physical hard disks indirectly via virtual hard disks managed by the hypervisor. Direct access, or pass-through disk access, is possible but less common and used for specific performance or software requirements. VMs generally favor virtual disks for their flexibility and advanced feature integration.
Step-by-step explanation:
Do VMs ever directly access a physical hard disk?
Virtual machines (VMs) typically access physical hard disks in an indirect manner. A VM relies on the virtualization software to create a virtual hard disk, which is usually a file or set of files on the host’s file system. This virtual disk acts like a physical disk to the VM, but it is actually managed by the host system’s storage. Direct access to a physical hard disk, known as pass-through disk access, is possible but not common. This feature allows a VM to bypass the host operating system's storage stack and interact directly with a physical disk. It is typically used in scenarios where a VM needs to perform high-performance tasks that require direct access to storage devices, or when a particular piece of software running within a VM must have direct access to physical storage hardware for functionality or licensing reasons. However, using pass-through disk access comes with tradeoffs, such as reduced flexibility and more complex storage management.
In everyday use, VMs generally interact with virtual disks that provide abstraction and flexibility, as well as integration with advanced features like snapshots, cloning, and dynamic resizing. The hypervisor or virtual machine monitor (VMM) mediates all I/O requests from the VM, translating them into operations on the physical hard disk. Therefore, while VMs can directly access physical hard disks, it is more common for them to use virtualized storage provided by the hypervisor.