> ## Documentation Index > Fetch the complete documentation index at: https://docs.tensormesh.ai/llms.txt > Use this file to discover all available pages before exploring further. # Glossary / Vocabulary > Plain-language definitions of the terms used throughout the Tensormesh Operator docs. 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. |