Google Cloud Fractional G4 Uses vGPU, Not MIG. Here Is Why That Matters.
Google Cloud announced fractional G4 VMs at GTC 2026 in March. The pitch is straightforward. The RTX PRO 6000 Blackwell Server Edition is a 96 GB GDDR7 GPU. Most workloads do not need all 96 GB. So Google slices one physical GPU into fractions (1/8, 1/4, 1/2) and sells you only what you need. Pay less, get less. Simple.
What Google does not say in the announcement, but does say in the documentation, is how that slicing works. The fractional G4 shapes use NVIDIA vGPU. Not MIG. That is a specific technical choice with specific security consequences, and the distinction matters if you are putting anything sensitive on a fractional instance.
This post covers what fractional G4 is actually built on, what NVIDIA's own documentation says about vGPU isolation versus MIG isolation, the Virtual GPU Manager's CVE history over the past two years, and what all of this means for workloads that care about tenant separation.