SQL Server licensing is the per-core model on Enterprise and Standard editions, with CAL-on-Server as the small-deployment alternative. The Admodum read on the editions, the virtualisation rules, the high-availability and disaster-recovery mechanics, and the Azure Hybrid Benefit.
SQL Server runs in two principal commercial editions for production deployments. Enterprise Edition carries the full feature set: AlwaysOn Availability Groups, online operations, partitioning, advanced security, in-memory OLTP, machine-learning services, advanced analytics. Standard Edition carries the mid-range feature set: basic HA (database mirroring, basic Availability Groups), buffer-pool extension, smaller capacity limits, no online operations beyond a narrower set, no advanced analytics.
The Developer Edition (free, non-production) and the Express Edition (free, capability-limited) sit alongside the commercial editions for development and small-deployment scenarios. The Web Edition (per-core, hoster-only) sits in a separate licensing surface for service-provider deployments.
The per-core licensing model applies on Enterprise and Standard. Each physical core on the host (or each vCPU on a virtualised deployment under host-level licensing) requires a SQL Server core licence. The per-core minimum is four cores per processor: a host with one processor and two cores requires four core licences; a host with one processor and four cores also requires four core licences; a host with one processor and eight cores requires eight core licences. The wider EA framework against which the SQL Server portfolio is licensed sits at the Enterprise Agreement overview; the wider editorial sits in the Microsoft pillar.
Virtualisation introduces two licensing models. Under host-level licensing (licensing all physical cores on the host) the buyer carries unlimited SQL Server VM density on that host, provided every physical core is licensed and SA is active. This is the high-density model and is structurally favourable where a host runs many SQL VMs.
Under per-VM licensing the buyer licenses each individual VM by vCPU count, with a four vCPU per VM minimum. This is the low-density model and is structurally favourable where a host runs few SQL VMs and a substantial portion of the host runs non-SQL workloads (web, application, file, print).
The arithmetic decides the model. A host with 64 physical cores running 12 SQL VMs at 4 vCPU each: host-level licensing requires 64 Enterprise core licences; per-VM licensing requires 48 (12 VMs × 4 vCPU each) Enterprise core licences; per-VM wins by a margin. The same host running 32 SQL VMs at 4 vCPU each: host-level licensing requires 64 cores; per-VM requires 128 cores; host-level wins. The wider Windows Server licensing surface that often sits underneath SQL Server sits at the Windows Server core licensing spoke.
SA on SQL Server enables the failover-rights entitlement. A buyer with SA on the primary Enterprise SQL Server licence holds a passive replica at no incremental SQL licence cost, provided the passive replica meets the failover-rights criteria (a true passive instance, used only for failover; no active queries; no reporting load; no backup load beyond the standard failover-replication maintenance).
The failover-rights entitlement extends in current SQL Server versions to a primary plus a synchronous secondary plus an asynchronous DR replica (under specific deployment patterns and SA-bearing terms). The misuse pattern is the principal SAM-audit false positive on SQL Server: a passive replica that is queried for reporting becomes an active replica and requires its own licence; the buyer-side artefact is the replica-mode attestation.
The wider AlwaysOn architecture surface sits at the SQL Server AlwaysOn spoke (forthcoming); the wider SA framework sits at the Software Assurance benefits spoke.
SQL Server is the principal Azure Hybrid Benefit target. SQL Server SA on the on-prem estate applies to Azure SQL Database (managed PaaS), Azure SQL Managed Instance and SQL Server on Azure VMs. The arithmetic against the PAYG line runs above 50 percent on most SKUs; on Managed Instance Enterprise the saving above 80 percent against the licence-included PAYG line is typical.
The Enterprise-to-Standard Step-Up entitlement under SA (one Enterprise Edition core licence covers up to eight Standard Edition cores on Azure) is the second-order benefit. A buyer with surplus Enterprise SA after on-prem consolidation captures an outsized Hybrid Benefit pool against the Azure workload; the pool runs against the Standard-tier Managed Instance and the Standard-tier Azure VM at the eight-to-one ratio.
The wider Azure Hybrid Benefit framework sits at the Azure Hybrid Benefit spoke; the wider MACC framework against which the consumption burns sits at the Azure MACC design spoke.
SQL Server is consistently in the top three Microsoft SAM-audit scopes. The audit examines four principal axes: the per-core inventory (every host, every core, every active SQL instance), the virtualisation model declaration (host-level versus per-VM, with the corresponding core-count reconciliation), the SA position (every SQL core licence, every SA term-end), and the failover-replica attestation (every passive replica, every DR replica, the use-mode declaration).
The frequent false-positive patterns: a passive replica queried for reporting (loss of failover-rights entitlement, requires separate licensing); a per-VM-licensed host that has been re-clustered such that VMs move across non-licensed hosts (the license-mobility 90-day rule applies); a Standard Edition instance running on hardware that exceeds the Standard Edition memory or core caps (the workload is under-licensed by edition); a Developer Edition instance used for non-development purposes (audit catches with a release-build attestation).
The buyer-side artefacts to hold against the SQL Server estate are: the per-host inventory (every host, every processor, every core, every SQL instance, every edition), the virtualisation-model declaration (host-level versus per-VM, per-cluster), the SA position (every SQL core licence, every SA term-end, every Step-Up entitlement, every license-mobility transition), the failover-replica register (every passive replica, every DR replica, the use-mode attestation), the Azure Hybrid Benefit register (every on-prem SA licence applied to an Azure workload), the renewal-time disposition.
The renewal-time conversation is then a negotiation against artefacts. The publisher's renewal proposal carries the SQL Server SA renewal across the inventory; the buyer's decision is per-host, against the artefacts; the SA drops, the SA retentions, the host-versus-per-VM modelling, the Hybrid Benefit applications and the Step-Up exercises are taken on shared arithmetic.
The wider engagement sits in the Microsoft practice; the aggregated reading list sits in the Microsoft knowledge hub; active renewal moments route to the Renewal Programme; active audit moments route to Audit Defence. The wider SAM audit framework sits at the SAM audit anatomy spoke; the wider True-Up framework sits at the True-Up mechanics spoke.
The operating-system foundation against which most SQL Server workloads run.
The SA-mediated bridge that delivers the largest single SQL Server saving.
The maintenance overlay that enables failover rights, license mobility and Step-Up.
A senior Admodum Microsoft advisor will read your per-host inventory, your virtualisation-model declaration, your SA position and your Hybrid Benefit application against your renewal and audit posture on a private call. Active audit moments route to Audit Defence.