Reference
Glossary
FundamentalEvery acronym and concept used across this site, in plain English. Search by term, abbreviation, or meaning - or filter by topic. Each card links to where the idea is explained in depth.
218 terms
A
ACID Transactions
ACIDAtomicity, Consistency, Isolation, Durability - the guarantees that make a database write reliable. Modern lakehouse table formats bring ACID to data lakes.
Activation Checkpointing
Trading compute for memory: discard intermediate activations during the forward pass and recompute them in the backward pass.
Activation-aware Weight Quantization
AWQPost-training 4-bit weight quantization that protects the most salient weight channels (chosen by activation magnitude), preserving accuracy.
AI Agent
An LLM-driven system that plans, calls tools, and acts over multiple steps toward a goal - not just a single chat response.
AI-Q
An agentic deep-research assistant (NVIDIA Blueprint / VAST Foundation Stack). Plans a question into sub-questions, retrieves repeatedly with reflection, then writes a cited report - RAG wrapped in an agent loop.
Apache Arrow
A columnar in-memory data format (plus Arrow Flight RPC) that moves tabular data between systems with zero serialization overhead. VAST DB's SDK speaks Arrow so query results stream straight into pandas, Spark, or GPU frames.
Apache Iceberg
An open table format that brings warehouse features - schema evolution, time travel, ACID - to files in a data lake.
Apache Spark
A distributed engine for large-scale data processing and ETL across a cluster - a workhorse of data pipelines.
Application Programming Interface
APIA defined interface for software to call a service. Agents use APIs as tools; models are themselves served behind inference APIs.
Approximate Nearest Neighbor
ANNAlgorithms (HNSW, IVF) that find near-closest vectors quickly by trading a little accuracy for huge speed at billion-scale.
Attention
The mechanism that lets each token weigh the relevance of every other token. Produces Query, Key, and Value vectors per token.
Audit Database
AuditDBA queryable audit store built on VAST Database (SQL, Python SDK, or the GUI), alongside per-CNode JSON logs for SIEM. In multi-tenant clusters, tenant managers can query their own audit records.
B
Bidirectional Encoder Representations from Transformers
BERTAn encoder-only transformer that reads text in both directions. The basis for many embedding and reranking models used in retrieval.
BlueField
NVIDIA's DPU product line. BlueField-3 pairs ~400 Gb/s networking with 16 Arm cores to run networking, storage, and security as an on-NIC infrastructure OS, freeing host CPU cores. BlueField-4 (2026, Vera Rubin) doubles networking to 800 Gb/s via ConnectX-9, adds a Grace CPU and PCIe Gen6, and offloads KV-cache / inference context-memory to a petabyte NVMe tier.
Business Intelligence
BIDashboards, reports, and ad-hoc analytics over business data. The traditional consumer of the data warehouse, now sharing the lakehouse with AI workloads.
Byte Pair Encoding
BPEThe dominant tokenization algorithm. Iteratively merges frequent character pairs into subword tokens, balancing vocabulary size against sequence length.
C
Central Processing Unit
CPUThe general-purpose processor that orchestrates a system - data loading, scheduling, and offload - while GPUs do the parallel math.
Centroid
The center point of a cluster of vectors. Clustered ANN indexes compare a query against centroids first to pick which cluster to search, pruning the rest of the dataset.
Change Data Capture
CDCTracking and streaming row-level inserts, updates, and deletes as they happen, so downstream systems stay in sync without full reloads. VAST DataBase's fine-grained mutable chunks make cross-table CDC simple at scale.
Chunking
Splitting documents into passage-sized pieces before embedding, so retrieval returns focused, relevant context rather than whole files.
CNode
A stateless compute node in DASE that serves protocols and runs logic. Because it holds no persistent state, CNodes scale independently of capacity and any CNode can serve any data.
CNode-X
A class of NVIDIA-Certified GPU servers that run the VAST AI Operating System directly on GPU infrastructure - unifying analytics (Sirius), vector search, RAG, and agent runtimes on one platform.
Column Chunk
VAST DataBase's fundamental on-flash unit: a ~32 KB columnar chunk carrying its own footer of metadata (projections, sort keys, and min/max + count statistics) in SCM, with no separate metadata manager. Roughly 1/4000th the size of a Parquet row group, so selective queries read one chunk instead of scanning a whole row group.
Context / Memory
The information an agent keeps available - short-term (the prompt/context window) and long-term (retrieved from a store) - to stay coherent.
Context Memory Storage
CMXThe first rack-scale implementation of NVIDIA STX. A shared tier of Ethernet-attached flash ('G3.5') tuned to hold KV cache close to the GPUs, lowering time-to-first-token for long-context and agentic inference.
Context Window
The maximum number of tokens a model can attend to at once (e.g. 8K, 128K, 1M). Longer context costs more memory, largely via the KV cache.
Continuous Batching
Adding and removing requests from a running batch every step instead of waiting for a fixed batch - keeps the GPU busy and lifts throughput.
Coolant Distribution Unit
CDUThe heat exchanger that isolates the clean coolant loop over the chips' cold plates from the facility water loop. Mandatory once a rack passes the ~25 kW air-cooling ceiling.
Copy-on-Write
CoWA snapshot/clone technique that writes only changed data and shares the rest by pointer, so the snapshot copies nothing. VAST's V-Tree adds a new root reusing existing subtrees, making snapshots near-free.
Cosine Similarity
A score from -1 to 1 measuring the angle between two embeddings. Closer to 1 means more semantically similar - the usual relevance metric.
Cost per Token / Tokens per Watt
The economic KPIs of inference at scale. Once power - not chip price - is the constraint, what matters is dollars per million tokens and tokens generated per watt, not raw FLOPS.
cuBLAS
NVIDIA's GPU BLAS library - the dense matrix-multiply (GEMM) engine underneath training and inference.
CUDA
NVIDIA's parallel-computing platform and programming model. The foundation almost every GPU AI library is built on.
CUDA-X
NVIDIA's collection of 400+ domain-specific accelerated libraries (cuDNN, cuBLAS, RAPIDS, NCCL, cuVS…) layered on CUDA. The breadth every framework optimizes for is the real competitive moat.
cuDF
A GPU DataFrame library (part of RAPIDS) with a pandas-like API. Accelerates data prep and ETL by running it on the GPU.
cuDNN
CUDA Deep Neural Network library - GPU-optimized primitives (convolutions, attention, normalization) used by PyTorch and TensorFlow.
cuVS
CUDA Vector Search - GPU-accelerated nearest-neighbor index build and search, powering fast vector databases for RAG.
D
DASE
Disaggregated Shared-Everything - VAST's architecture that separates compute from NVMe storage so every node sees all data with no bottleneck.
Data Gravity
The tendency of large datasets to pull compute toward them, because data is costly and slow to move. It pushes AI jobs to run where the data lives - or forces expensive copies.
Data Lake
A store for raw data of any type (structured or not) at massive scale and low cost - flexible but easy to turn into a 'data swamp'.
Data Pipeline
The automated flow that ingests, cleans, transforms, and serves data for analytics or AI. The unglamorous foundation every model depends on.
Data Processing Unit
DPUA programmable network processor (e.g. NVIDIA BlueField) that offloads networking, storage, and security from the CPU.
Data Warehouse
A store for cleaned, structured data optimized for fast SQL analytics and BI. Reliable and governed but rigid and pricier per TB.
DBox
A fault-tolerant storage enclosure (a JBOF) holding the NVMe SSDs and SCM. Each DBox is fronted by two DNodes in an active-active pair, so losing one DNode never takes the box offline.
Decode
The memory-bandwidth-bound phase that generates output one token at a time, reading the growing KV cache each step.
DeepSpeed
Microsoft's training-optimization library, best known for ZeRO sharding and CPU/NVMe offload that let huge models train on limited GPU memory.
DGX / HGX
NVIDIA's reference GPU server platforms. HGX is the baseboard OEMs build on; DGX is NVIDIA's own fully-integrated system.
DGX Cloud
NVIDIA-managed GPU clusters rented through hyperscaler clouds - the full NVIDIA stack as a service, with no hardware to own.
DGX SuperPOD
NVIDIA's reference data-center design that clusters many DGX systems with InfiniBand into a turnkey AI supercomputer.
Digital Twin
A live, physically accurate virtual replica of a real asset (factory, robot, grid) used to test and optimize before acting in the real world.
Direct Preference Optimization
DPOA simpler alternative to RLHF that optimizes directly on preference pairs with a classification-style loss - no separate reward model or RL loop.
Disaggregated Serving
Running prefill and decode on separate GPU pools so each scales independently - the design behind NVIDIA Dynamo.
DNode
A storage enclosure (DBox) of NVMe SSDs plus a small Storage Class Memory tier. DNodes hold all the data; CNodes reach every DNode over NVMe-oF, so compute and capacity scale separately.
DOCA
NVIDIA's software framework for programming BlueField DPUs. DOCA Memos, introduced with STX, handles KV-cache communication and storage between GPUs and the context-memory tier.
Domain Randomization
Randomizing simulation parameters (lighting, textures, physics) during training so a model generalizes robustly to the messy real world.
Dot Product / Inner Product
The sum of element-wise products of two vectors. Large when vectors both align and are long; the building block of cosine similarity and the negative-inner-product metric.
Dynamic Random-Access Memory
DRAMMain system (host) memory. Larger but far slower than GPU HBM - used to stage data and to offload optimizer state or KV cache.
E
Element Store
VAST's foundational data structure - a flat, metadata-rich store where files, objects, table rows, and streams are all 'elements,' enabling true multi-protocol access to one copy of data.
Embedding
A vector of numbers that represents the meaning of a token, word, or document. Similar meanings land close together in vector space.
Encryption Group
The unit of at-rest encryption (AES-XTS-256, a data key wrapped by a key-encryption key). Scoped per cluster, per tenant, or per group; at least one per tenant gives crypto isolation and tenant-scoped crypto-erase - at the cost of cross-tenant data reduction.
ETL / ELT
Extract-Transform-Load (transform before storing) vs Extract-Load-Transform (load raw, transform later in the warehouse). The core data-movement patterns.
Euclidean Distance
L2Straight-line distance between two vectors, the square root of the summed squared differences. Sensitive to magnitude, unlike cosine. VAST exposes it in SQL as array_distance().
Eventual Consistency
A weaker model where replicas only converge to the latest value over time, so reads can briefly return stale data. Common in geo-distributed stores; what DataSpace's strict model avoids.
F
Feature Store
A system that serves consistent, precomputed model inputs ('features') to both training and inference, preventing train/serve skew.
Fine-tuning
Continuing training of a pretrained model on a smaller, task-specific dataset to specialize its behavior.
FLOPs / TFLOPS
Floating-point operations - the unit of compute. Training cost ≈ 6 × params × tokens FLOPs; a GPU's TFLOPS (trillions/sec) sets how fast it clears.
FP16 / BF16
16-bit floating-point formats. BF16 keeps FP32's exponent range with less precision and is the default for training and inference on modern GPUs.
FP4 / NF4
4-bit formats. FP4 is Blackwell's lowest-precision compute mode; NF4 ('normal float 4') is the data type QLoRA uses to freeze a 4-bit base model.
FP8
8-bit floating point, accelerated natively on Hopper/Blackwell GPUs. Roughly doubles throughput vs BF16 with careful scaling.
G
GeForce / RTX
RTXNVIDIA's consumer/workstation GPU line. Capable for local inference and fine-tuning, but lacks the HBM, NVLink, and scale of data-center cards.
Generative Pre-trained Transformer
GPTThe decoder-only transformer family (GPT-3/4) that popularized large-scale next-token pretraining. Most modern LLMs follow its blueprint.
Global Namespace
A single, consistently addressable view of data across many clusters and clouds - the foundation of VAST DataSpace, so one file, object, or table is reachable from every site with no copies to sync.
GPTQ
A one-shot post-training method that compresses LLM weights to 3–4 bits with minimal accuracy loss using approximate second-order information.
GPU Architecture Generations
NVIDIA's roughly yearly datacenter GPU families - Hopper (H100/H200) → Blackwell (B200/GB200) → Blackwell Ultra (B300) → Vera Rubin → Rubin Ultra → Feynman - each adding memory, lower-precision math, and scale.
GPUDirect Storage
GDSA direct data path from NVMe/network storage into GPU memory, skipping a CPU bounce buffer - critical for feeding data-hungry GPUs.
Grace CPU
GraceNVIDIA's Arm-based server CPU, linked to Blackwell GPUs over NVLink-C2C in the GB200/GB300 superchips so CPU and GPU share fast, coherent memory.
Gradient
The signal telling each parameter how to change to reduce error. Computed in the backward pass and synchronized across GPUs via NCCL.
Graphics Processing Unit
GPUThe massively parallel processor that runs AI training and inference. Its memory bandwidth and VRAM size are the usual bottlenecks.
Group Relative Policy Optimization
GRPOAn RL method (popularized by DeepSeek) that ranks a group of sampled answers against each other, dropping PPO's value network. Key to reasoning models.
Grouped-Query Attention
GQAA middle ground: groups of query heads share K/V heads. Used by Llama 2/3 to balance quality and KV-cache size.
H
High-Bandwidth Memory
HBMStacked, ultra-fast memory on data-center GPUs (e.g. HBM3e). Its bandwidth (TB/s) sets the ceiling for decode-phase token speed.
HNSW
Hierarchical Navigable Small World - a graph-based ANN index prized for high recall and low query latency.
Hybrid Model
A model that interleaves Transformer attention layers with SSM (Mamba) layers. Only the few attention layers grow a KV cache, so it reaches near-Transformer quality at a fraction of the long-context memory.
I
Indestructible Snapshot
An immutable, ransomware-proof snapshot whose deletion - and whose policy - require multi-factor challenge-response tokens from VAST Support before expiry. Designed to defeat rogue admins and insider attacks.
InfiniBand
IBA low-latency, high-throughput network fabric used to connect GPU servers across a cluster, typically with RDMA.
InfiniBand NDR
NDRThe 400 Gb/s-per-port generation of InfiniBand used to wire GPU clusters together with RDMA and very low latency.
INT8 / INT4
8- and 4-bit integer formats for weight quantization. INT4 can shrink a model ~4× versus BF16 for memory-constrained deployment.
Inter-Token Latency
ITLThe gap between consecutive streamed tokens - essentially TPOT viewed per-step. Steady, low ITL is what makes streaming output read smoothly.
Inverted File Index
IVFAn ANN index that clusters vectors into cells and only searches the nearest few at query time - trading a little recall for a large speed-up over brute force.
J
JAX
A composable, XLA-compiled array framework popular for research and large-scale training, with automatic differentiation and easy hardware acceleration.
Just a Bunch of Flash
JBOFA dense, controller-light enclosure of NVMe flash drives exposed over the network (NVMe-oF) rather than fronted by a traditional storage controller. In VAST, a DBox is a fault-tolerant JBOF that CNodes mount directly.
K
K-means Clustering
An algorithm that partitions vectors into K clusters around centroids, iterating until they settle. VAST runs it on a sample to build and continuously recluster its vector index.
KV Cache
Stored Key and Value vectors for tokens already processed, so the model doesn't recompute them each step. The dominant memory cost of long-context inference.
L
Lakehouse
Combines a lake's cheap, open storage with a warehouse's reliability (ACID transactions, schemas) via table formats like Iceberg or Delta.
Large Language Model
LLMA neural network trained on vast text to predict the next token. Powers chat, code, and reasoning assistants. Most are decoder-only transformers.
Locally-Decodable Erasure Coding
VAST's data-protection scheme (e.g. 146+4) that survives drive failures at ~2.7% overhead while rebuilding from only a fraction of the stripe - far cheaper and faster to recover than triple replication.
Low-Rank Adaptation
LoRAFreezes the base model and trains tiny low-rank adapter matrices (~0.1–1% of params), making fine-tuning cheap and portable.
M
Mamba
A selective state space model that rivals transformers on long sequences with linear-time inference and a constant-size state - no growing KV cache.
Megatron-LM
NVIDIA's reference implementation of large-scale model parallelism (tensor/pipeline/expert) - the backbone of many frontier training stacks.
MGX
NVIDIA's open modular server reference spec - 100+ configurations across CPU/GPU combos and generations - that OEMs build many SKUs from.
Min/Max Pruning
A data-skipping technique where each chunk stores the minimum and maximum value of its column, so a selective query reads only chunks whose range can contain the value and skips the rest before any bytes move. VAST DataBase keeps these statistics per ~32 KB chunk for fine-grained pruning.
Mixture of Experts
MoEA sparse architecture where each token is routed to only a few 'expert' sub-networks. Gives large total capacity while activating few params per token.
MLX
Apple's array framework for machine learning on Apple Silicon, using the unified memory of M-series chips.
Model Context Protocol
MCPAn open standard for connecting agents to tools and data sources through a uniform interface, so the same tool server works across different agent frameworks.
Model FLOPs Utilization
MFUThe fraction of a GPU's peak FLOPS actually spent on useful model math. 30–50% is typical at scale; the rest is lost to memory stalls and communication.
Multi-Head Attention
MHAStandard attention with many independent heads, each with its own K/V. Highest quality but largest KV cache.
Multi-head Latent Attention
MLADeepSeek's technique that compresses K/V into a low-rank latent vector, slashing KV-cache memory while keeping MHA-like quality.
Multi-Layer Perceptron
MLPThe feed-forward sub-layer in each transformer block - two linear layers with a nonlinearity. Holds the bulk of a model's parameters.
Multi-Query Attention
MQAAll query heads share a single K/V head, shrinking the KV cache dramatically at a small quality cost.
Multitenancy
Running many fully-isolated tenants on one shared-everything cluster. Isolation is enforced in software (namespace, identity, network, keys, QoS) rather than by physically partitioning the array - so no stranded capacity and no noisy neighbors.
MXFP4 / NVFP4
Block-scaled 4-bit floating-point formats - a shared scale per small block of values - that make FP4 accurate enough for inference on Blackwell.
N
NCCL
NVIDIA Collective Communications Library - the optimized all-reduce/all-gather routines that synchronize gradients across many GPUs in training.
Negative Inner Product
NIPThe dot product negated, so 'smaller is closer' like a distance. VAST's array_negative_inner_product() ranks magnitude-aware similarity directly in SQL.
Neocloud
A GPU-first specialist cloud (e.g. CoreWeave, Lambda, Crusoe) built on OEM HGX systems - typically far cheaper than hyperscalers but with fewer managed services.
Non-Volatile Memory Express
NVMeA protocol for fast SSD storage over PCIe. NVMe-over-Fabrics extends it across the network - the basis of disaggregated flash storage.
NVIDIA AI Blueprint
A reference AI workflow from NVIDIA - runnable sample code built from NIM microservices that developers fork and customize. The starting point VAST Foundation Stacks turn into production pipelines.
NVIDIA BlueField-4 STX
STXNVIDIA's AI-native storage reference architecture (GTC 2026). Inserts a dedicated context-memory tier between GPUs and storage so KV cache can be persisted and reused across a pod instead of recomputed. Built on BlueField-4, Spectrum-X, and Vera Rubin.
NVIDIA Dynamo
A datacenter-scale inference framework that disaggregates prefill and decode and routes requests to where the KV cache already lives.
NVIDIA Inference Microservices
NIMPrebuilt, optimized models packaged as containers with standard API endpoints - deploy a tuned model anywhere without assembling the serving stack yourself.
NVIDIA NeMo
An end-to-end framework for pretraining, fine-tuning, and aligning LLMs and multimodal models at scale, built on Megatron and PyTorch.
NVIDIA Omniverse
A platform for building and running physically based 3D simulations and digital twins, connected via the OpenUSD scene format.
NVL144 / NVL576
Next-gen rack-scale NVLink domains on the Vera Rubin roadmap - NVL144 (144 GPUs) and Rubin Ultra's NVL576 (576 GPUs in one rack), succeeding today's NVL72.
NVL72
A GB200/GB300 rack of 72 Blackwell GPUs joined by NVLink into one giant GPU - 18 compute trays + 9 switch trays in one NVLink-5 domain.
NVLink
NVIDIA's high-speed GPU-to-GPU interconnect, far faster than PCIe. Lets many GPUs share data as if one large accelerator.
NVSwitch
The switch chip that wires many GPUs into an all-to-all NVLink fabric - the backbone of an NVL72 rack's single NVLink domain.
O
OpenUSD
USDUniversal Scene Description - an open standard for describing, composing, and exchanging complex 3D worlds across tools.
Optimizer State
Extra per-parameter data (e.g. Adam's momentum and variance) kept during training - often the largest chunk of training memory (~16 bytes/param).
Origin / Satellite
DataSpace's consistency model: per global folder, one cluster is the Origin holding the authoritative copy and write lease; the others are Satellites caching locally under read leases. A remote write is proxied to the Origin.
P
PagedAttention
vLLM's technique that stores the KV cache in non-contiguous 'pages' like OS virtual memory, eliminating fragmentation so more requests fit per GPU.
Parallelism dimensions
DP/TP/PP/EP/CPWays to split a training job across GPUs: Data, Tensor, Pipeline, Expert, and Context parallelism - combined as 3D/4D parallelism for frontier models.
Parameter
paramA learned weight in the network. Model size (7B, 70B, 405B) counts parameters; more params generally means more capability and more memory.
Parquet
A columnar file format that compresses well and is fast to scan - the default storage for analytics and lakehouse tables.
Peripheral Component Interconnect Express
PCIeThe standard bus linking CPUs, GPUs, NICs, and SSDs. Slower than NVLink, so GPU-to-GPU traffic avoids it where possible.
Polaris Control Plane
VAST's free, Kubernetes-native control plane for deploying, monitoring, and managing clusters across regions and clouds from one pane of glass - the management substrate of the AI OS.
Post-Training Quantization
PTQQuantizing a trained model's weights/activations with little or no retraining. Fast and cheap (GPTQ, AWQ) versus retraining-based QAT.
Predicate & Projection Pushdown
Sending a query's filters (predicates) and the set of needed columns (projection) down to the storage layer, so only matching rows and requested columns are read - rather than scanning everything and filtering in compute.
Prefill
The compute-heavy phase that reads the whole prompt in parallel and populates the KV cache before any token is generated.
Prefix Caching
Reusing the KV cache of a shared prompt prefix (e.g. a system prompt) across requests so it is computed once, not per request.
Pretraining
The expensive first phase: training a model from scratch on trillions of tokens to learn general language and knowledge.
Product Quantization
PQCompresses vectors by splitting them into sub-vectors and encoding each against a small codebook, shrinking the index so billions of vectors fit in memory.
Prompt
The input text given to a model. In serving it becomes the 'prefill' the model reads before generating a response.
PyTorch
The dominant deep-learning framework for research and production. Defines and trains models with Python and runs them on GPUs via CUDA.
Q
Quality of Service
QoSPer-tenant / view / bucket / user performance policy with max caps (containment) and min guarantees (a protected floor), static or capacity-scaled. Enforced by injecting I/O latency in 0.1-second windows - the noisy-neighbor control on a shared cluster.
Quantization
Storing weights/activations in fewer bits (e.g. INT8, INT4) to cut memory and speed up inference, trading a little accuracy.
Quantization-Aware Training
QATSimulating low-precision arithmetic during training so the model learns to tolerate it - higher accuracy than PTQ at the cost of a training run.
Quantized LoRA
QLoRALoRA on top of a 4-bit (NF4) frozen base, letting a 65B model fine-tune on a single 48 GB GPU.
Queries Per Second
QPSRequests handled per second - the throughput axis serving systems trade against latency. Larger batches raise QPS but can hurt TTFT.
Quota
Hard and soft limits on capacity and file/inode count, applied per directory, user, group, or tenant (with a grace period and up to 3-level nesting). Counts physical bytes used, so it reflects data reduction.
R
RadixAttention
SGLang's KV-cache reuse scheme that shares cached prefixes across requests via a radix tree - automatic prefix caching for branching prompts.
RAPIDS
NVIDIA's suite of GPU-accelerated data-science libraries (cuDF, cuML, cuGraph) for end-to-end analytics without leaving the GPU.
RDMA over Converged Ethernet
RoCERDMA carried over an Ethernet fabric instead of InfiniBand - the low-latency transport SuperNICs use to move GPU-to-GPU traffic on Ethernet-based AI clusters.
ReAct
Reason + Act - the agent loop pattern where the model alternates between reasoning steps and tool calls, observing each result before deciding the next move.
Read / Write Lease
The decentralized permissions that keep DataSpace strictly consistent: a Satellite serves cached data under a read lease; a write takes the Origin's write lease, which then invalidates every read lease so no site serves stale data.
Recall
For approximate search, the fraction of the true nearest neighbours an index actually returns (e.g. 99% recall) - the accuracy traded away for ANN's speed at scale.
Reference Architecture
A pre-validated blueprint spanning compute, network, storage, and software - tested for power, thermals, and signal integrity - so an AI cluster goes live in weeks, not months.
Reinforcement Learning
RLTraining an agent by trial and error against a reward signal - often run at massive scale in simulation for robotics and control.
Reinforcement Learning from AI Feedback
RLAIFLike RLHF, but preferences are labeled by an AI judge instead of humans - scaling alignment data far more cheaply.
Reinforcement Learning from Human Feedback
RLHFAligning a model to human preferences: train a reward model from human comparisons, then optimize the policy against it (classically with PPO).
Remote Direct Memory Access
RDMALets one machine read/write another's memory directly over the network, bypassing the CPU and OS - key to fast distributed training and storage.
Reranking
A second-stage model that re-scores the top retrieved chunks for relevance, sharpening what the LLM finally sees.
Retrieval-Augmented Generation
RAGFetching relevant documents at query time and feeding them to an LLM, so answers are grounded in your data instead of just model memory.
Root Mean Square Normalization
RMSNormA lightweight layer-normalization variant used in Llama-class models - rescales activations by their RMS, with no mean subtraction.
Rotary Position Embedding
RoPEEncodes token position by rotating query/key vectors by an angle proportional to position. Standard in modern LLMs and key to extending context length.
S
Scalable Hierarchical Aggregation and Reduction Protocol
SHARPNVIDIA in-network computing that performs all-reduce inside InfiniBand switches, cutting collective-communication time in large training jobs.
Service-Level Objective
SLOA target a service commits to, e.g. 'p99 TTFT under 500 ms.' Serving systems batch and schedule to maximize throughput without breaking the SLO.
SGLang
A fast LLM serving engine featuring RadixAttention prefix caching and a structured generation language for complex, branching prompts.
Silhouette Score
A 0-to-1 grade of cluster quality - how tight a cluster is versus how separated from its neighbours. A low score flags a cluster that has drifted and should be reclustered.
Sim-to-Real
Transferring a policy trained in simulation to real hardware. The 'reality gap' is bridged with domain randomization and accurate physics.
Similarity-Based Data Reduction
Global reduction that finds and encodes byte-level similarity across all data - not just exact-match dedup - shrinking footprints (including embeddings and model data) beyond classic compression.
Sirius
GPU SQLA roadmap CNode-X compute tier bringing GPU-accelerated SQL (RAPIDS cuDF/cuVS) to VAST DB; VAST reports ~44% query-time reduction, moving analytics from CPU-bound to GPU-bound on the same data.
Sliding Window Attention
SWARestricts each token to attend only to a fixed window of recent tokens, capping KV-cache growth for long sequences (used by Mistral).
Solid-State Drive
SSDFlash-based persistent storage. NVMe SSDs feed datasets and store checkpoints; their aggregate bandwidth gates how fast GPUs can be fed.
State Space Model
SSMA non-attention sequence architecture (e.g. Mamba) that carries a fixed-size recurrent state. Scales linearly with sequence length instead of quadratically.
Stochastic Gradient Descent
SGDThe base optimization algorithm: nudge weights down the loss gradient on mini-batches. Adam adds momentum and per-parameter scaling on top.
Storage Class Memory
SCMA fast, persistent memory tier that acts as VAST's write buffer: incoming data lands in SCM, is reduced and shaped, then flushed to cheap QLC flash - giving low write latency on bulk-economical media.
Strict Consistency
A guarantee that once a write commits, every reader anywhere sees the new value immediately - no stale reads. VAST DataSpace provides it across sites via read/write leases.
Structured Query Language
SQLThe standard language for querying and manipulating relational data. Increasingly the interface for analytics over lakehouse and vector data too.
Superchip
GB200 / GB300A package joining Grace CPU(s) and Blackwell GPU(s) over NVLink-C2C as one coherent unit. The GB200/GB300 superchip is the building block of the NVL72 rack.
SuperNIC
ConnectX-8A NIC purpose-built for GPU-to-GPU (east-west) AI traffic. NVIDIA's ConnectX-8 SuperNIC delivers up to 800 Gb/s of RDMA/RoCE with GPUDirect - distinct from a DPU's infrastructure-offload role. ConnectX-9 is the Vera Rubin generation, integrated into the BlueField-4 DPU.
Supervised Fine-Tuning
SFTFine-tuning a base model on curated prompt→response demonstrations so it follows instructions - the first post-training stage before preference alignment.
Synthetic Data
Machine-generated training data from simulation. Cheap, perfectly labeled, and able to cover rare 'edge cases' real data misses.
T
Tenant
An isolated administrative and data domain on a VAST cluster (vastdata_tenant). Each tenant has its own Element Store root, identity provider, encryption keys, quotas, QoS, and network rules; a cluster scales to 10,240 tenants.
Tenant Admin
A delegated administrator scoped to a single tenant - manages its views, quotas, local identity provider, S3 keys, and tenant roles, but cannot create tenants, make VIP pools, add identity providers, or see cluster hardware. Contrast with Cluster Admin.
Tensor Core
Specialized GPU units that do matrix-multiply-accumulate at low precision (FP16/FP8/FP4) - the engine behind AI throughput.
TensorFlow
Google's production deep-learning framework with broad deployment tooling. Largely supplanted by PyTorch for research but still widely deployed.
TensorRT
NVIDIA's inference optimizer and runtime that fuses layers, selects fast kernels, and quantizes a trained model into an efficient engine. TensorRT-LLM and NIM build on it.
TensorRT-LLM
TRT-LLMNVIDIA's compiler/runtime that builds optimized inference engines for LLMs - fused kernels, quantization, in-flight batching.
Thermal Design Power
TDPThe sustained heat a chip is designed to dissipate, in watts. Data-center GPU TDP has climbed from ~700 W (H100) toward ~1,400 W (B300), forcing the shift to liquid cooling.
Throughput vs Latency
Throughput = tokens/sec across all users; latency = time-to-first-token and per-token speed for one user. Serving tunes the trade-off.
Time Per Output Token
TPOTAverage time to generate each token after the first, set by the decode phase. TTFT + TPOT × tokens predicts total response time.
Time To First Token
TTFTLatency from request to the first generated token - dominated by the prefill phase. The key metric for how responsive a stream feels.
Token
The atomic unit a model reads and writes - a word piece, character, or symbol. Text is split into tokens before the model sees it; output is generated one token at a time.
Tokenization
Converting raw text into a sequence of token IDs the model can process. The vocabulary and rules determine how many tokens a given string costs.
Tool Use
Letting a model call external functions, APIs, or code to fetch data or take actions beyond text generation.
Transformer
The architecture behind nearly all modern LLMs. Stacks of self-attention + feed-forward layers that let every token look at every other token.
Triton Inference Server
NVIDIA's production server for deploying models from any framework with dynamic batching, concurrency, and multi-model hosting.
V
V-Tree
The wide, shallow metadata tree VAST uses to index the Element Store. Its low depth keeps lookups fast even at exabyte scale, underpinning the platform's flat global namespace.
VAST AgentEngine
A runtime for hosting and governing AI agents next to the data, exposing platform tools over MCP so agents act on live data with low latency and central control.
VAST AI Operating System
AI OSVAST's framing of its stack as one operating system for AI - storage, database, streaming, serverless compute, and agents converging onto a single platform rather than separate products.
VAST Data Platform
A unified data platform combining storage, database, and compute on disaggregated shared-everything (DASE) architecture for AI at scale.
VAST DataBase
A columnar table format built into the VAST platform - an Iceberg/Delta-style alternative that stores analytical tables natively on VAST storage, with no separate Parquet files or metastore. Mutable and ACID, not an OLTP database.
VAST DataEngine
An event-driven serverless compute fabric that runs functions on data where it lands - triggers, Python functions, and containerized engines - so processing happens in-situ with no ETL copy. GA Nov 2025.
VAST DataSpace
A global namespace spanning edge, on-prem, and every cloud so the same data is addressable everywhere with no copies, using an Origin/Satellite model for strict consistency. Lets training and inference follow GPU capacity.
VAST Event Broker
A Kafka-API-compatible streaming engine built into the platform with stateless brokers - durability comes from VAST storage, and streams land directly as queryable Database tables. GA Mar 2025.
VAST Foundation Stacks
Open-source implementations that turn NVIDIA AI Blueprints into production pipelines on the VAST AI OS - a serverless DataEngine ingest pipeline feeding a unified VastDB store, served by NVIDIA NIMs. Launch stacks cover RAG, AI-Q, and VSS.
VAST InsightEngine
VAST's real-time RAG stack co-engineered with NVIDIA (BlueField-3, Spectrum-X, NIM, GPUDirect Storage) that auto-embeds data on ingest for instant, always-fresh retrieval.
VAST VectorStore
Vector search built into the VAST platform, indexing embeddings alongside source data for RAG at massive scale.
Vector Database
A store that indexes embeddings and finds the nearest vectors to a query fast - the retrieval engine behind RAG and semantic search.
Vector Search
Finding items by meaning rather than keywords, by locating the closest embedding vectors to a query vector.
Vera Rubin
RubinNVIDIA's next-generation platform succeeding Grace Blackwell, pairing the Vera CPU with Rubin GPUs. The compute platform that STX and CMX are designed to feed.
Video RAM
VRAMA GPU's on-board memory. Holds the model weights, KV cache, and activations - running out of VRAM is the most common deployment limit.
Video Search & Summarization
VSSAn NVIDIA Blueprint (and VAST Foundation Stack) that ingests live or archived video, describes each segment with a vision-language model, and makes it searchable and summarizable in natural language.
VIP Pool
A group of virtual IPs that CNodes serve protocols through. A pool can be pinned to specific CNodes (cnode_ids) and assigned to a tenant + VLAN - giving that tenant a dedicated serving path while data stays on the shared DNode pool.
Vision-Language Model
VLMA model that takes both images and text as input and reasons over them jointly - e.g. describing a photo or reading a chart. Adds a vision encoder in front of an LLM.
vLLM
A high-throughput LLM serving engine. Its PagedAttention manages the KV cache like virtual memory to pack many requests onto a GPU.
VMS Realm
RealmThe RBAC building block in the VAST Management Service: a set of object types plus the allowed actions (create/view/edit/delete) on them. A custom realm can be scoped to one tenant to delegate administration.
W
World Model
A model that learns the dynamics of an environment and predicts future states, letting agents 'imagine' outcomes - e.g. NVIDIA Cosmos.
Z
ZeRO / FSDP
Techniques that shard model params, gradients, and optimizer state across GPUs so models too big for one card can still train.
References & credits
The explanations across this portal draw on the primary papers, vendor documentation, and open-source projects below. Credit to their authors and maintainers - follow the links to go deeper.
- NVIDIA Technical Blog & Developer Docs →
NVIDIA
- Dynamo - datacenter-scale inference framework →
NVIDIA
- CUDA, cuDNN, cuVS, cuDF / RAPIDS libraries →
NVIDIA
- NVIDIA Omniverse & OpenUSD →
NVIDIA
- Cosmos world foundation models →
NVIDIA
- Attention Is All You Need (the Transformer) →
Vaswani et al., 2017
- GQA: Grouped-Query Attention →
Ainslie et al., 2023
- DeepSeek-V2 (Multi-head Latent Attention) →
DeepSeek-AI, 2024
- Mamba: Linear-Time Sequence Modeling →
Gu & Dao, 2023
- QLoRA: Efficient Finetuning of Quantized LLMs →
Dettmers et al., 2023
- Efficient Memory Management for LLM Serving (PagedAttention / vLLM) →
Kwon et al., 2023
- ZeRO: Memory Optimizations Toward Training Trillion-Parameter Models →
Rajbhandari et al., 2019
- RAG: Retrieval-Augmented Generation for Knowledge-Intensive NLP →
Lewis et al., 2020
- HNSW: Efficient and robust approximate nearest neighbor search →
Malkov & Yashunin, 2016
- Lakehouse: A New Generation of Open Platforms →
Armbrust et al., CIDR 2021
- Apache Iceberg, Spark & Parquet →
Apache Software Foundation
- The VAST Data Platform →
VAST Data