In addition to virtual machine (VM) instances, Compute Engine alsooffers bare metal instances. Bare metal instances provide direct access to thehost server's CPU and memory, without Compute Engine's hypervisor inthe middle. Bare metal instances also expose all CPU performance counters andbuilt inCPU accelerators.

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

When you select a machine type with a name that contains-metal, you create abare metal instance in the same way that you 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 networkand subnetwork.

Workload recommendations for bare metal instances

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

• Workloads that require direct, non-hypervisor mediated access to the hostserver'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 threadpinning, such as financial exchanges or other realtime workloads
• Workloads that use non-virtualizable,on-CPU chip accelerators such asQAT, 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 metalinstances. The features not available with bare metal instances include:

• gVNIC or VirtIO support: bare metal instances don't run a hypervisor, anddon't support the gVNIC or VirtIO network drivers for virtual networkinterfaces. Instead, they use theIntel IDPF LAN PF device driver.
• Multiple network interfaces: each bare metal instance has only a singlenetwork interface. You can use Dynamic Network Interfacesto configure additional network interfaces. For more information about usingmultiple network interfaces with a compute instance, seeMultiple network interfaces.
• SCSI disk interface: like allthird generation and latermachine series, bare metal instances use only the NVMe disk interface.
• Attached disks: bare metal instances can use onlyGoogle Cloud Hyperdisk storage. C4, A4X Max, and Z3 also support Local SSD disks with baremetal instances.
• Windows OS support: bare metal instances don't provide support for Windowsimages.
• Interactive serial console: bare metal instances have a read-only serialconsole, but not an interactive one.
• Virtual Trusted Platform Module (vTPM): features such as Secure Boot,vTPM-enabled Measured Boot, and otherShielded VM features,includingShielded Google Kubernetes Engine (GKE) nodesare not available with bare metal instances. You must disable shielded nodesto use bare metal machines with GKE.For more information, seeDisabling GKE nodes.

• On host maintenance: the maintenance behavior for most bare metal instancesmust be set toTERMINATE. Live migration is not feasible because bare metalinstances are not virtual instances. C4 and Z3 bare metal instances, whichsupport LSSD can be set toRESTART IN PLACE.

• CPU utilization monitoring: CPU utilization monitoring isn't availablewith bare metal instances. If you install the Ops Agent on a bare metalinstance, you can instead use the metricOS Reported CPU %.

Machine series with bare metal machine types

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

A4X Max machine series

A4X Max bare metalinstances are powered by NVIDIA GB300 Grace Blackwell Ultra Superchips.The A4X Max machine series offers one bare metal machine type:

• a4x-maxgpu-4g-metal comes with 144 vCPUs and 960 GB of memory.

A4X Max uses NVIDIA Grace CPUs with Arm Neoverse V2 cores, which are connectedto four NVIDIA B300 Blackwell GPUs. You can attach Hyperdisk Balanced and Hyperdisk Balanced High Availability disksto A4X Max bare metal instances. 12,000 GB of Local SSD storage isautomatically attached to A4X Max bare metal instances. A4X Max bare metalinstances offer up to 3,600 Gbps of network bandwidth.

The A4X Max machine series is part of theaccelerator-optimized machine family,which is designed for AI, ML, and HPC workloads.

C4 machine series

C4 bare metal instances arepowered by 6th generation Intel Xeon Scalable processors(code-named Granite Rapids). You can create C4 bare metal instances with 288vCPUs, up to 2,232 GB of memory, and 18 TiB of local Titanium SSDstorage. Bare metal instances require a dedicated host server. If you create a bare metalinstance, then that compute instance is the only one that can run on the hostserver.

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

• standard: 288 vCPUs and 1,080 GB of memory.
• highmem: 288 vCPUs and 2,232 GB of memory.

C4 is built onTitanium whichoffloads processing from the host CPU for network processes and Titanium SSDdisk I/O. You can attach Hyperdisk Balanced and Hyperdisk Extreme disks to C4 bare metal instances.C4 bare metal instances offer up to 100 Gbps network bandwidth for standardnetworking and up to 200 Gbps with per VM Tier_1 networking performance.

The C4 machine series is part of thegeneral-purpose machine family, whichhas excellent price-performance with flexible vCPU to memory ratios.

C4A machine series

This feature is subject to the "Pre-GA Offerings Terms" in the General Service Terms section of theService Specific Terms. Pre-GA features are available "as is" and might have limited support. For more information, see thelaunch stage descriptions.

For information about access to this release, see the access request page.

C4A bare metal instances arepowered by Google Axion processors. You can createhighmem C4A bare metalinstances with thec4a-highmem-96-metal machine type, which comes with 96vCPUs and 768 GB of memory.

C4A is built onTitanium whichoffloads processing from the host CPU for network processes and Titanium SSDdisk I/O. You can attach Hyperdisk Balanced, Hyperdisk Extreme, and Hyperdisk ML disks to C4A bare metalinstances. C4A bare metal instances offer up to 50 Gbps network bandwidthfor standard networking and up to 100 Gbps with per VM Tier_1 networking performance.

C4D machine series

C4D instances are poweredby 5th generation AMD EPYC Turin processors. You can create C4D bare metalinstances with 384 vCPUs and up to 3,072 GB of memory.Bare metal instances require a dedicated host server. If you create a bare metalinstance, then that compute instance is the only one that can run on the hostserver.

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

• c4d-highcpu-384-metal comes with 384 vCPUs and 768 GB of memory.
• c4d-standard-384-metal comes with 384 vCPUs and 1,488 GB of memory.
• c4d-highmem-384-metal comes with 384 vCPUs and 3,072 GB of memory.

C4D is built onTitanium which uses network offloads. Youcan attach Hyperdisk Balanced and Hyperdisk Extreme disks to C4D bare metal instances. Local SSDdisks aren't available for C4D bare metal instances, but are available with C4DVMs created with a machine type that ends in-lssd. C4D bare metal instancesoffer up to 100 Gbps network bandwidth for standard networking and up to200 Gbps network bandwidth for per VM Tier_1 networking performance.

The C4D machine series is part of the general-purpose machine family. To learnmore about the machine types and features of C4D, seeC4D machine series.

C3 machine series

C3 is the firstmachine series to offer a bare metal machine type. C3 instances are powered by4th generation Intel Xeon Scalable processors (code-named Sapphire Rapids). Youcan create C3 bare metal instances with 192 vCPUs and up to 1,536 GB of memory.Bare metal instances require a dedicated host server. If you create a bare metalinstance, then that compute instance is the only one that can run on the hostserver.

The amount of memory available to your bare metal instance depends on whichmachine 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 onTitanium which uses network offloads. Youcan attach Hyperdisk Balanced and Hyperdisk Extreme disks to C3 bare metal instances. Local SSDdisks aren't available for C3 bare metal instances, but are available with C3VMs created with a machine type that ends in-lssd. C3 bare metal instancesoffer up to 100 Gbps network bandwidth for standard networking and upto 200 Gbps with per VM Tier_1 networking performance.

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

X4 machine series

TheX4 machine seriesoffers these predefined machine types:

• x4-480-6t-metal comes with 480 vCPUs and 6,144 GB of memory.
• x4-480-8t-metal comes with 480 vCPUs and 8,192 GB of memory.
• x4-960-12t-metal comes with 960 vCPUs and 12,288 GB of memory.
• x4-960-16t-metal (previouslyx4-megamem-960-metal) comes with 960 vCPUsand 16,384 GB of memory.
• x4-1440-24t-metal (previouslyx4-megamem-1440-metal) comes with 1,440vCPUs and 24,576 GB of memory.
• x4-1920-32t-metal (previouslyx4-megamem-1920-metal) comes with 1,920vCPUs and 32,768 GB of memory.

X4 instances are powered by the 4th generation Intel Xeon Scalable processor(code-named Sapphire Rapids) andTitanium.X4 instances can be used with only Hyperdisk Balanced and Hyperdisk Extreme storage. Local SSD disksaren't available for X4 instances. X4 supports up to 100 Gbps networkbandwidth for standard networking.Bare metal instances require a dedicated host server. If you create a bare metalinstance, then that compute instance is the only one that can run on the hostserver.

The X4 machine series is part of thememory-optimized machine family,which provides the most compute and memory resources of anyCompute Engine machine family and higher memory-to-vCPU ratiosthan general-purpose machine types.

Z3 machine series

Z3 is the firstmachine series to offer Titanium SSD disks with a bare metal machine type.Z3 instances are powered by 4^th generation Intel Xeon Scalableprocessors (code-named Sapphire Rapids).Bare metal instances require a dedicated host server. If you create a bare metalinstance, then that compute instance is the only one that can run on the hostserver.

Z3 offers only a single bare metal machine type:z3-highmem-192-highlssd-metal. This machine type comes with 192 vCPUs,1,536 GB of memory, and 72,000 GiB of local Titanium SSD storage.

Z3 is built onTitanium, whichuses network offloads. You can attach Hyperdisk Balanced and Hyperdisk Extreme disks to Z3 bare metalinstances. Z3 bare metal instances offer up to 100 Gbps network bandwidthfor standard networking and up to 200 Gbps with per VM Tier_1 networking performance.

The Z3 machine series is part of the storage-optimized machine family, andprovides high density, high performing Titanium SSD storage. Z3 provideshigh vCPU to Titanium SSD capacity ratios of any machine series offeredby Google Cloud.

Supported OS images for bare metal instances

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

For information about the regional availability of A4X Max bare metal instances,seeGPU locations.

What's next

• Create and start a Compute Engine bare metal instance.