Azure Cobalt Virtual Machines are based on Cobalt 100, Microsoft’s first custom-designed Arm-based processor. The chip became generally available in 2024 alongside the first Cobalt VM series, marking Microsoft’s entry into the custom silicon market in the cloud, following AWS with Graviton and Google with Axion.
Cobalt 100: Microsoft’s Custom Arm Chip
Cobalt 100 is based on the Arm Neoverse N2 architecture and was optimized by Microsoft specifically for cloud workloads. Unlike standard x86 processors designed for a broad range of applications, Microsoft can make optimizations with Cobalt 100 specifically tailored to cloud workload requirements: higher core density, better energy efficiency, and deeper integration with Microsoft’s network and storage infrastructure. The first VM series based on Cobalt are the Dpsv6 and Dplsv6 series, designed for general-purpose workloads and offering up to 128 vCores and 512 GB RAM.
Microsoft reports up to 50% better performance per watt for Cobalt VMs compared to comparable x86 Dv5 VMs. In practice, this means the same workload can be run on fewer or cheaper VMs, enabling direct cost savings. For containerized workloads on Azure Kubernetes Service (AKS), Cobalt nodes are particularly suitable since Kubernetes natively supports Arm64 nodes and multi-arch container images are now standard.
Arm64 in the Cloud: Challenges and Opportunities
Using Arm64 VMs requires attention to software compatibility. Modern languages like Java, Python, Go, Rust, and Node.js support Arm64 without restrictions. Container images must be available as Arm64 or multi-arch images. Older proprietary software or statically compiled x86 binaries cannot run on Arm64. For most cloud-native applications based on open-source stacks, however, migration to Cobalt VMs is straightforward and offers immediate cost and performance benefits, particularly noticeable in large AKS clusters and web-tier deployments.
Typical Use Cases
Frequently Asked Questions
What is the Cobalt 100 processor?
Cobalt 100 is Microsoft's first custom-designed Arm-based processor, based on the Arm Neoverse N2 architecture. Microsoft optimized it specifically for cloud workloads, similar to how AWS developed Graviton and Google developed Axion.
Which VM series use Cobalt 100?
The Dpsv6 and Dplsv6 series are the first VM series based on Cobalt 100. They are designed for general-purpose workloads and offer up to 128 vCores and 512 GB RAM.
Are all Linux applications compatible with Arm64?
Most modern Linux applications natively support Arm64 or via multi-arch container images. Some older or proprietary software may require recompilation. Container workloads on AKS benefit particularly since Docker and Kubernetes fully support Arm64.
How do Cobalt VMs compare to AWS Graviton?
Both offer similar price-performance improvements over x86 (approximately 40-60%). AWS Graviton has been on the market longer and has broader availability. Cobalt 100 is optimized for the Azure stack and benefits from Microsoft's infrastructure optimizations.
