Glossary
The terms this documentation uses, and what they mean here.
Active controller — The controller currently serving the console and API and owning the virtual IP. Exactly one at a time. See High availability.
Agent — The process on each host that the control plane instructs. Its version is tracked separately from the control plane’s.
Anti-affinity group — A label keeping VMs in the same group on different hosts, so a single host failure cannot take all of them.
Appliance mode — A node locked down so SSH lands in the VS-HCI shell rather than a
Linux prompt, with operator accounts removed from the sudo group. The default.
Availability zone — A group of hosts sharing a failure domain, and the unit within which workloads are placed and restarted. See Availability zones.
Chassis — A host as the virtual networking layer knows it.
Console — The web interface. Also, confusingly but conventionally, a VM’s screen. Context distinguishes them.
Console name — The DNS name resolving to the virtual IP, and the name on the deployment’s TLS certificate.
Controller — A node running the control plane. A controller is usually also a host.
DR placeholder — The replica of a protected VM at the paired site. A real VM with real disks and reserved memory that cannot be started there, because its disks are the receiving end of a live mirror.
Evictable — A VM that may be powered off to make room for a more important one during a failover.
Fabric — An isolated routed network domain, a VRF. Either VLAN-based or overlay. See Fabrics.
Fabric MTU — The MTU available inside an overlay network: the underlay MTU minus 58 bytes of encapsulation.
Fencing — Cutting a lost host off shared storage before restarting its workloads elsewhere. If it fails, nothing is restarted. See Failover and recovery.
GDS — Global Distributed Switch — A switch providing networks that exist identically on every host in its uplink. Five kinds: L2, L3, management, storage and replication. See Distributed switches.
Geneve — The encapsulation carrying overlay traffic between hosts. Costs 58 bytes, and runs over UDP 6081.
Host — A server running workloads. A host may also be a controller.
HyShell — The internal name for the VS-HCI shell.
Hyperconverged — A host contributing both compute and storage. The normal role.
Hyperion — The platform’s internal engineering name. It appears in the CLI banner and prompt, in service names and in filesystem paths. The product is VS-HCI.
Join token — The short token a node presents to enrol. It buys a place in the Approvals queue, not membership.
L3-out — An overlay fabric’s edge: two hosts through which it reaches the physical network. See Routing and NAT.
LUN — A block device exported over iSCSI. One VM disk is one LUN.
Maintenance mode — A host excluded from scheduling so its workloads can be moved off before planned work.
Overlay / underlay — The overlay is the virtual network guests see. The underlay is the physical network carrying the tunnels.
PENDING (VM) — The platform is not going to start this VM, and says why. Distinct from
STOPPED, which someone chose. Nothing restarts a PENDING VM automatically.
Preflight — A probe checking hardware is fit for a storage mode before building it. See Replicated storage.
Pool — Storage on one host that VM disks live in.
Priority (controller) — The election ranking. Lower is more preferred.
Root shell — Authorized access to the operating system underneath, granted by a signed challenge and time-limited. See Root shell access.
Scope — What CLI commands currently act on: the cluster, or one host.
Standby controller — A controller replicating the active one’s database, ready to take over. Answers reads; returns 409 to writes.
Storage VIP — An address following whichever node is active in a replicated storage pair.
Task — A unit of asynchronous work. See Tasks.
Term — A counter incremented at each controller election. A climbing term means repeated elections.
Transit network — The one network in an overlay fabric with a port onto the physical VLANs, used by the L3-out to reach your router.
Uplink — A bond of physical NICs behind a bridge, with a member on each participating host. The foundation of every distributed switch. See Uplinks and bonds.
Virtual IP (VIP) — The address of the deployment. It follows the active controller, which is why it is the address to use for everything.
VSOS-HCI — The operating system image every node runs.
VS-Hypervisor — A single-node deployment. Same product, no peers.
VS-HCI — The clustered product this documentation describes.
VTEP — A host’s tunnel endpoint address on the underlay, created when an overlay switch is built.