Azure VM series retirements: what the announcement doesn't spell out

Microsoft has announced the retirement of several long-running VM families, including F, Fs, Fsv2, Lsv2, G, Gs, Av2, Amv2, and B-series, effective November 15, 2028. That sounds straightforward, until you read the details.

The B-series confusion

Only the original Bv1 line is retiring, not the newer Bv2. The announcement isn’t explicit about this, but Microsoft uses “B-series” to refer to the classic SKUs (B1s, B2ms, and so on), while Bv2 remains active. If you’re auditing exposure by name alone, you’ll flag the wrong fleet.

The Fsv2 replacement isn’t a clean swap

Fsv2 has two candidate replacements, and neither is a perfect match:

• Fsv2 → Fasv6: not a perfect match. Fasv6 drops Simultaneous Multithreading (SMT), so each vCPU now maps to a full physical core. That’s better performance, at a higher cost.
• Fsv2 → Dlsv6: technically possible, but requires care. Dlsv6 uses NVMe disk controllers, which complicates a direct migration.

Key dates to keep in mind

• 3-year reserved instances: no new purchases or renewals after November 15, 2025.
• 1-year reserved instances: no new purchases or renewals after November 15, 2027.
• Pay-as-you-go: ends November 15, 2028.

For once, Microsoft’s documentation is genuinely helpful here: it maps older VM families to modern ones (Dasv5, Dsv5, Dasv6, and so on) and calls out where migration blockers like NVMe, MANA, or Generation 2-only support might appear.

What to do with this

If you’re managing reservations, now is the time to review your exposure to these retiring SKUs, especially Fsv2 and Bv1, and start validating newer generations for performance, cost, and quota fit. The 3-year reservation cutoff is the closest deadline; if you’re still buying 3-year terms on an affected family, that window closes first.