Bare metal, virtual machines, and containers
Decide per role, not once for the cluster, whether a component runs on a physical machine, in a virtual machine, or in a container. Each role needs something different from its platform, so most deployments are mixed. The platform that fits the Chunkservers is not the platform that fits a test client. This page matches the platform to the role. The hardware pages linked from here cover what each role needs from its machine. Operating systems covers a separate decision: which operating systems the components run on.
Virtualization trades consistency for convenience
A hypervisor carries the I/O and network traffic of its guests on a host whose resources are shared. Performance is lower than the same hardware gives directly. Latency changes with the load of neighbors on the same host. The guest cannot detect this cause. In return, virtualization gives operational convenience. Guests are provisioned from templates or APIs in minutes, cloned, snapshotted, migrated between hosts, and controlled by orchestration tools. Capacity also grows without buying hardware. Bare metal is the reverse of each point: consistent I/O and predictable latency, direct access to disks and network interfaces, and full control of the hardware. Bare metal costs the hardware itself, the space, power, and cooling under it, slower setup, and a hands-on visit when a machine fails. Cost divides the same way: bare metal is bought up front and cheap to keep. Virtual capacity, cloud instances above all, is paid for as it is used. Check the sum of those payments over years before you call virtual capacity the cheaper option.
Contention on the host reaches the guest only as latency without a visible cause. A virtualized deployment therefore depends more on monitoring than the same cluster on bare metal. A disk or network bottleneck that the platform hides has to be read from the cluster's own figures.
Chunkservers belong on bare metal
The Chunkservers store the data and carry its whole traffic, so the Chunkservers get the costs of virtualization and little of its convenience. The more throughput-bound the workload (media streaming, analytics, model training), the more the consistency of physical hardware matters. Run Chunkservers on physical machines with dedicated disks and dedicated network interfaces. The machine has disks that the Chunkserver accesses directly and as whole devices (Chunkservers). A Chunkserver does not access a virtual disk that way. The machine's network port carries the data throughput of the cluster (separated backbone network).
Where Chunkservers run as guests anyway, check the failure domain. A copy is stored on a different Chunkserver. Two Chunkserver guests on one physical host therefore put two of those copies on one machine. The two copies then share one power supply and one failure. Keep Chunkserver guests on separate hosts, each with disks of its own rather than a shared datastore.
The Master Server tolerates a virtual machine
The Master Server needs stability and single-core speed rather than disk throughput (Master Servers). A virtual machine can provide both. The virtual machine needs a reliable layer underneath. The storage that holds the metadata and the network to the clients must be dependable. This one machine answers every metadata operation of every client. Anything lost or delayed under that machine therefore affects every operation. The machine settings that matter to the Master Server, power saving among them, are set on the physical host, not in the guest.
Clients run anywhere
The client needs the least from its platform. Virtual machines and containers are both fine, whether the mount is made directly, provided by a CSI driver in Kubernetes, or reached over NFS. Client machines covers what a client machine needs, FUSE 3 above all. That page also covers the count of mounts and machines that the workload's data rate has to be divided by.
Containers change the packaging, not the needs
Putting a server component in a container relaxes none of the demands above. A containerized Chunkserver still needs disks that it accesses directly and as whole devices. A containerized Master Server still needs dependable storage, a dependable network, and a core that is not contended. A container shares the host's kernel and competes for the host's resources with everything else on the host. A platform that pools disks into shared volumes or oversubscribes CPU therefore recreates the virtualized case above, not a third option. Evaluate a container platform by whether it passes those resources through unchanged.
A mixed deployment is the usual shape
The recommendations combine. Chunkservers run on bare metal for the storage performance. The Master Server runs in a virtual machine where that flexibility is useful. Clients run wherever the applications already run. Virtual machines or cloud instances host what is short-lived or secondary anyway: labs, tests, prototypes, and standby environments. This combination splits the cluster along its actual demands. The data path gets the consistency of physical hardware. Everything else gets the convenience of virtualization.