Microsoft's Arm-based Cobalt 100 CPU now live and powering Azure VMs

Microsoft's Cobalt 100 Arm CPUs have reached general availability in its Azure cloud, creating another non-x86 option for running VMs in the Redmondian cloud.

The processors power three instance types: the Dpsv6, Dplsv6, and Epsv6.

The first two instance types are intended for general purpose computing. The Dpsv6 instances offer VMs ranging from two virtual CPUs and 8GiB of memory at list price of $51 a month all the way to monsters with 96 vCPUs and 384GiB of RAM that will set you back $2,460. Microsoft reckons they're suited to web and application servers, small to medium databases, or running caches.

Keen-eyed readers may have noticed that the VMs above offer 4GiB of memory per vCPU. The Dplsv6 instance type halves that, and prices come down accordingly to $45 a month for the smallest machine and $2,172 for the 96-core beast. Redmond recommends these to run microservices, small databases, caches, and gaming servers.

The Epsv6 VMs offer 8GiB per vCPU. Prices pop to $67 a month for a pair of vCPUs, and $3,230 for 96 vCPUs. That config makes them suitable for relational database servers, large databases, data analytics engines, and in-memory caches.

The prices quoted above can shrink if you sign up for long-term use or can tolerate the risk that comes with using spot instances.

As our sibling publication The Next Platform noted when Microsoft announced the Cobalt 100, the chip appears to be based on the Neoverse Compute Subsystems N2 design offered by Arm as a template on which to build processors, was built by TSMC on a five nanometer process and has 128 cores – the result of combining two 64-core tiles. It's unclear why Microsoft doesn't offer a 128-core VM.

Microsoft is of course publicizing lovely performance numbers: the Cobalt-powered VMs are apparently up to 1.4 times faster "compared to previous generations of Azure Arm-based VMs," and also up to 1.5 times faster when running Java workloads, and perform twice as well when running web servers, .NET applications, and in-memory cache applications.

"These VMs also support 4x local storage IOPS (with NVMe) and up to 1.5x network bandwidth compared to the previous generation Azure Arm-based VMs," Microsoft's launch post states.

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Two things to note here.

One is that all the Cobalt-equipped instances use the same 3.4GHz processor, and omit temporary storage. Microsoft of course allows users to add Azure storage, with several types to choose from. But the software giant has not said what storage configuration produced the performance benchmarked above.

The other is that Microsoft hasn't explained what it means by "previous generations of Azure Arm-based VMs." Microsoft's last effort in this field runs Ampere's Altra processor.

Readers may recall that Oracle owns a third of Ampere, and could take control of the chip designer in 2027. Maybe Microsoft wants us to know it's got Big Red's tame chip designer beat without insulting it to its face.

The new VMs are "broadly available" in Azure's Canada Central, Central US, East US 2, East US, Germany West Central, Japan East, Mexico Central, North Europe, Southeast Asia, Sweden Central, Switzerland North, UAE North, West Europe, and West US 2 regions. They're also "coming soon" to the Australia East, Brazil South, France Central, India Central, South Central US, UK South, West US 3, and West US regions. "Soon" means in 2024. ®