A vSphere HA safeguard that reserves spare capacity for failover. Anything that would eat into that reserve, like powering on or migrating in a VM or increasing a reservation, is blocked.
Also called vSphere HA admission control.
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In the Ultra Transcenders books
Each book explains Admission control in context, with comparison tables and the common traps.
Terms in this definition
- vSphere HA
When a host fails, this cluster capability restarts its VMs elsewhere; through VM Component Protection and VM Monitoring it also reacts to storage and VM failures.
- Capacity
A reserved block of compute for a tenant whose size is fixed by its SKU; Fabric F SKUs express it in capacity units (CUs). Workspaces assigned to it unlock features like Copilot, and from F64 upwards people with free licences can view Power BI content.
- LIKE
Compares strings with a pattern that can contain the % and _ wildcards. Because it only understands character patterns, searching big volumes of text this way is much slower than using full-text search.
Related terms
- Azure Policy for Kubernetes
Admission control for Kubernetes based on Gatekeeper v3, installed as an AKS add-on or, on other clusters, an Arc extension. It acts as a webhook so that non-compliant pods are rejected by Azure Policy definitions set to Deny.
- Host failures cluster tolerates
In vSphere HA admission control, this number says how many hosts can fail with the cluster still able to recover. You then decide how the reserved capacity is defined: dedicated failover hosts, slot policy or a percentage of cluster resources.