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VirtualCenter (vCenter) licenses explained
Purpose
This article explains the importance of a VirtualCenter license.
Resolution
The following two models are available to implement in your production environment:
Centralized License Server – When you use this licensing model, a single license file holding your licensed entitlement is stored on a license server. The license server manages an entire license pool making licenses available to one or more hosts. When a host requires a particular licensed functionality, the license key for that entitlement is temporarily checked out from the license pool. Unused license keys are released to the pool, becoming available again to any host. This simplifies license administration by allowing allocation and re-allocation of licenses from a single location.
Single Host – When you use this licensing model, the license files are stored on individual VMware ESX hosts. There is no automatic distribution of unused licenses, but there is no dependence on an external connection for licensing.
The Centralized implementation directs that each server it is connected to, is licensed and managed by VirtualCenter server. Thus, you need to have a VirtualCenter license in your account to create a centralized license file for Server-Based production model.
Licenses for the VirtualCenter Server and for the VirtualCenter add-on features like the VirtualCenter Agent, VMotion, VMware HA, and VMware DRS are only valid for the centralized model, which has the following advantages:
Instead of maintaining individual license keys on every host and tracking all of them manually, the license server allows all licenses available and being used to be administered from a single location.
Future license purchasing decisions are simplified because the new licenses available might be allocated and re-allocated using any combination of ESX host form factors. The same 32 processors worth of licenses, for instance, may be used for sixteen 2-ways, eight 4-ways, four 8-ways, or two 16-ways (or any combination thereof, totaling 32 processors).
Ongoing license management is also simplified by allowing licenses to be assigned and re-assigned on an as-needed basis as the needs of an environment change, such as when hosts are added or removed or premium features like VMotion, VMware DRS, or VMware HA need to be transferred to different hosts.
During periods of license server unavailability, VirtualCenter and ESX Servers using served licenses are unaffected because they rely on cached licensing configurations for the duration of a 14-day grace-period.
