Bare metal instances on Compute Engine

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In addition to virtual machine (VM) instances, Compute Engine also offers bare metal instances. Bare metal instances provide direct access to the host server's CPU and memory, without Compute Engine's hypervisor in the middle. Bare metal instances also expose all CPU performance counters and built in CPU accelerators.

Bare metal instances on Compute Engine are consumed and managed in the same way as VM instances. Bare metal instances run on physical servers in Google data centers and are fully managed by Google.

Using a machine type with a name that ends in -metal, you create a bare metal instance just as you would create a VM instance. For example, you can:

• Attach Hyperdisk storage to a bare metal instance.
• Configure the network interface to attach to a VPC network and subnetwork.

Workload recommendations

Cloud native bare metal instances are generally not substitutes for VM instances, but they expand the types of workloads you can run on Compute Engine. Some of the use cases for bare metal instances are:

• Workloads that require direct, non-hypervisor mediated access to the host server's CPU and memory resources, primarily to run third-party hypervisors:
  • Networking security
  • CI/CD Pipelines
  • Third-party private clouds and VMware (through Google Cloud VMware Engine).
• Workloads that are sensitive to CPU performance
• Workloads that require direct access to CPU counters and process to thread pinning, such as financial exchanges or other realtime workloads
• Workloads that use non-virtualizable, on-CPU chip accelerators such as QAT, DLB, and IAA
• Workloads not licensed for virtual machine use

Differences between VM instances and bare metal instances

Almost all of the features of VM instances are available with bare metal instances. The features not available with bare metal instances include:

• gVNIC or VirtIO support: Bare metal instances don't use virtualized network interfaces, so they use the Intel IDPF LAN PF device driver.
• Multiple network interfaces: Each bare metal instance comes with only a single network interface, and you can't add network interfaces when creating the instance. For more information about using multiple networks with a compute instance, see Multiple network interfaces.
• SCSI disk interface: Like all third generation and later machine series, bare metal instances use only the NVMe disk interface.
• Persistent Disk or Local SSD disks: Bare metal instances can use only Google Cloud Hyperdisk storage.
• Windows OS support: Bare metal instances don't provide support for Windows images.
• Interactive serial console: Bare metal instances have a read-only serial console, but not an interactive one.
• Virtual Trusted Platform Module (vTPM): Features such as Secure Boot, vTPM-enabled Measured Boot, and other Shielded VM features, including Shielded GKE nodes are not available with bare metal instances.
• The maintenance behavior for bare metal instances must be set to TERMINATE. Live migration is not feasible because bare metal instances utilize an entire host server and are not virtual instances.
• CPU utilization monitoring isn't available with bare metal instances. If you install the Ops Agent on a bare metal instance, you can instead use the metric OS Reported CPU %.

Machine series with bare metal machine types

You can create a bare metal instance using machine types from the following machine series.

C3 machine series

C3 is the first machine series to offer a bare metal machine type. C3 instances are powered by 4th generation Intel Xeon Scalable processors (code-named Sapphire Rapids). You can create C3 bare metal instances with 192 vCPUs and up to 1,536 GB of memory.

The amount of memory available to your bare metal instance depends on which machine type you use:

• c3-highcpu-192-metal comes with 192 vCPUs and 512 GB of memory.
• c3-standard-192-metal comes with 192 vCPUs and 768 GB of memory.
• c3-highmem-192-metal comes with 192 vCPUs and 1,536 GB of memory.

C3 is built on Titanium which uses network offloads. You you can attach Hyperdisk Balanced and Hyperdisk Extreme disks to C3 bare metal instances. Local SSD disks aren't available for C3 bare metal instances, but are available with C3 VMs created with a machine type that ends in -lssd. C3 bare metal instances offer up to 100 Gbps network bandwidth for standard networking and up to 200 Gbps with per VM Tier_1 networking performance.

The C3 machine series is part of the general-purpose machine family, which has the best price-performance with the most flexible vCPU to memory ratios.

X4 machine series

The X4 machine series offers three predefined machine types:

• x4-megamem-960-metal comes with 960 vCPUs and 16,384 GB of memory.
• x4-megamem-1440-metal comes with 1,440 vCPUs and 24,576 GB of memory.
• x4-megamem-1920-metal comes with 1,920 vCPUs and 32,768 GB of memory.

X4 instances are powered by the 4th generation Intel Xeon Scalable processor (code-named Sapphire Rapids) and Titanium. X4 instances can be used with only Hyperdisk Balanced and Hyperdisk Extreme storage. Local SSD disks aren't available for X4 instances. X4 supports up to 100&nbspGbps network bandwidth for standard networking.

The X4 machine series is part of the memory-optimized machine family, which provides the most compute and memory resources of any Compute Engine machine family and higher memory-to-vCPU ratios than general-purpose machine types.

OS images

Because bare metal instances use the IDPF network driver, you can only use OS images that support IDPF.

Regional availability of bare metal instances

The following sortable table shows which bare metal machine types are available in each zone. You can filter the table rows by geographical location.

What's next

• For additional details about C3 instance hardware and features, review the specifications at C3 machine series.
• For additional details about X4 instance hardware and features, review the specifications at X4 machine series.
• Create and start a Compute Engine bare metal instance.