Glossary

Azure Local : Microsoft's on-premises hyperconverged infrastructure (HCI) solution, formerly Azure Stack HCI. Runs Azure services on-premises.

Cluster Shared Volume (CSV) : A shared storage volume accessible from all nodes in a Windows Server Failover Cluster. Used by VMFleet to store fleet VMs.

Collect Volume : A dedicated ReFS volume (200GB+) used by VMFleet to aggregate DiskSpd results from all fleet VMs.

DiskSpd : Microsoft's open-source storage performance benchmarking tool. VMFleet uses DiskSpd as the I/O workload generator inside fleet VMs.

fio (Flexible I/O Tester) : A cross-platform storage I/O benchmarking tool with extensive workload customization. Primarily used on Linux.

Fleet VM : A lightweight virtual machine deployed by VMFleet as part of the testing fleet. Runs Windows Server Core with DiskSpd.

HammerDB : An open-source database benchmarking tool supporting TPC-C (OLTP) and TPC-H (OLAP) workloads against SQL Server and other databases.

IOPS : Input/Output Operations Per Second. A key storage performance metric measuring the number of read/write operations the storage can handle.

iPerf3 : A network performance measurement tool for testing bandwidth, jitter, and packet loss over TCP, UDP, and SCTP.

JSON-lines : A text format where each line is a valid JSON object. Used for structured logging in this framework.

Latency : The time delay between issuing an I/O request and receiving the response. Measured in milliseconds. Lower is better.

Master Environment File : The master-environment.yml file containing all configuration variables tagged by solution.

PerfMon : Windows Performance Monitor. A built-in tool for collecting performance counter data from Windows systems.

RDMA (Remote Direct Memory Access) : A technology enabling direct memory access from one computer to another without involving the operating system. Used for high-speed storage networking in Azure Local.

SMB Direct : An enhancement to the SMB protocol that uses RDMA network adapters for high-throughput, low-latency data transfer.

Solution JSON : A generated JSON file containing only the variables relevant to a specific testing solution (e.g., vmfleet.json).

Storage Spaces Direct (S2D) : Microsoft's software-defined storage solution that pools local drives across cluster nodes into a highly available, scalable storage system.

stress-ng : A stress testing tool with 370+ stress tests for CPU, memory, cache, filesystem, and other system components.

Throughput : The amount of data transferred per unit of time. Measured in MB/s or GB/s. Higher is better.

VMFleet : A storage load generator that deploys a fleet of VMs running DiskSpd workloads across a Hyper-V cluster to stress-test Storage Spaces Direct.

Workload Profile : A predefined set of I/O parameters (block size, read/write ratio, random/sequential ratio, etc.) that defines a specific test scenario.