Off by default and unsupported on stretched clusters, clusters with fault domains or clusters under four hosts, this vSAN option keeps an operations reserve for internal operations and, optionally, a host rebuild reserve to repair data after a single host failure. New VMs cannot use the space it holds back.
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Terms in this definition
- vSAN
VMware's software-defined storage, which combines local devices across a cluster's ESX hosts into one shared datastore. Available as OSA or ESA, VCF can use it as principal storage.
- operations reserve
Space vSAN can optionally keep free for its own housekeeping. Off by default; a soft reservation that works together with the host rebuild reserve.
- Internal
The API Management VNet mode where the gateway can be reached solely through a private IP address.
- host rebuild reserve
Spare vSAN space, optional, kept so that data lost with one failed host can be repaired. Soft, like the operations reserve: it stops new VMs or power-ons from using it up. Stretched and two-node clusters lack support for it.
- Virtual machines
Infrastructure-as-a-service compute giving complete control of the operating system, making it a fit for lift-and-shift moves and for software relying on OS-level pieces like COM.
Related terms
- DTU model
Purchasing model for Azure SQL with Basic, Standard and Premium tiers and the licence bundled in; reserved capacity and Azure Hybrid Benefit aren't available.
- 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.
- Serverless
Compute tier for single Azure SQL databases that scales automatically, pauses when idle and charges by the second. It is offered in General Purpose and Hyperscale, not Business Critical, and reserved capacity does not apply.
- vCore model
For Azure SQL, buying compute by picking vCores, memory and storage individually; reserved capacity and Azure Hybrid Benefit both apply.
- vCore purchasing model
Buying Azure SQL by picking hardware, number of vCores, memory, storage and service tier. Serverless compute and reserved capacity come only with this option, not with DTUs.