Glossary / Vocabulary - Tensormesh User Documentation

Short definitions of the terms you’ll meet in these docs, grouped by area.

Tensormesh / LMCache

Term	Meaning
LMCache	A multi-process KV (key-value) cache for LLM inference. When requests share a prefix (system prompt, RAG context, prior turn), LMCache lets later requests reuse the earlier request’s attention KV tensors instead of recomputing them.
Tensormesh Operator (TMO)	The Kubernetes controller this chart installs. It watches `LMCacheEngine` resources and reconciles them into a DaemonSet of cache servers.
Engine	A running LMCache cache server pod (one per GPU node, via a DaemonSet). Created by the operator from an `LMCacheEngine` CR.
`LMCacheEngine`	The custom resource you write to declare an engine. Group/version `lmcache.lmcache.ai/v1alpha1`.
MP mode / `LMCacheMPConnector`	”Multi-process” mode — vLLM connects to the engine on the same node over shared-memory IPC (`hostIPC`). The connector ships KV blocks between vLLM and the engine.
L1 / L2	Cache tiers. L1 is local node memory (sized by `engine.spec.l1.sizeGB`). L2 is an optional shared backend (Redis, S3, filesystem).
KV cache hit	A later request reused stored KV blocks for a shared prefix — the win LMCache delivers. Visible as `prefix hits` in engine logs and faster TTFT.

Kubernetes

Term	Meaning
CRD (CustomResourceDefinition)	Extends the Kubernetes API with a new resource kind. Cluster-scoped. Here: `lmcacheengines.lmcache.lmcache.ai`.
CR (Custom Resource)	An instance of a CRD-defined kind, e.g. an `LMCacheEngine`.
Operator / controller	A program that watches CRs and reconciles them into lower-level objects (Deployments, DaemonSets, …).
DaemonSet	Runs one pod per matching node — the shape used for the engine (one per GPU node).
Deployment	Maintains N identical pods with rolling updates — the shape used for the operator.
Finalizer	A marker on a resource that blocks its deletion until a controller runs cleanup. The `LMCacheEngine`’s `lmcache.ai/cleanup` finalizer can block a namespace delete if the operator is gone.
Namespaced vs cluster-scoped	Namespaced resources are removed when their namespace is deleted; cluster-scoped ones (CRD, ClusterRole, ClusterRoleBinding) survive and must be cleaned up explicitly.
SCC (Security Context Constraint)	OpenShift’s per-pod security policy. Engine pods need the `privileged` SCC because they use `hostIPC`.
ServiceMonitor	A Prometheus Operator CR telling Prometheus what to scrape.

Helm

Term	Meaning
Chart	A versioned, packaged bundle of Kubernetes templates + default values.
Release	A named installation of a chart in a namespace. Helm stores its history (as Secrets) to enable upgrade/rollback.
Values / values file	User configuration that overrides chart defaults — supplied via `-f my-values.yaml` (preferred) or `--set`.
appVersion vs version	`version` is the chart’s version; `appVersion` is the version of the app it deploys. The operator image tag defaults to `appVersion`.
OCI artifact	A chart stored in a container registry (here GHCR) using OCI media types — pulled with `oci://…` instead of a classic HTTP repo.
Hook	A Job/pod Helm runs at a lifecycle point (pre-install, pre-delete, test). The chart’s pre-delete hook removes the engine CR before the operator.

Observability

Term	Meaning
OTLP	OpenTelemetry Protocol — how the engine ships metrics/traces to the Collector (gRPC on `:4317`).
OTel Collector	Receives OTLP from the engine and exports onward (Prometheus, Tempo, external backends). Managed by the OpenTelemetry Operator from a CR the chart creates.
Prometheus exporter (`:8889`)	The Collector port that re-exposes LMCache application metrics (`lmcache_*`) for scraping.
Collector internals (`:8888`)	The Collector’s own metrics (`otelcol_*`) — used to confirm data is flowing.
Tempo	A trace storage backend. The chart can deploy a `TempoMonolithic`; you view traces in your own Grafana via a Tempo data source.
`remoteWrite`	Pushing metrics to an external Prometheus-compatible endpoint (Grafana Cloud, Mimir, Thanos) instead of (or alongside) in-cluster scraping.

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