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Glossary

The terms you will meet throughout this documentation, in alphabetical order. For deeper technical detail, follow the links to the relevant pages.

  • Bundle (Vates VMS): The way Vates VMS is sold: a single subscription combining XCP-ng support licenses for all your hosts, one Xen Orchestra Appliance, and professional support from Vates. See Vates VMS bundle overview.

  • CR/DR (Continuous Replication / Disaster Recovery): Continuous Replication copies a VM at regular intervals to another storage repository, typically on a second site; Disaster Recovery plans use those replicas to restart your workloads quickly if the primary site is lost. See Xen Orchestra.

  • dom0: The privileged control domain of a Xen host. It has direct access to the hardware, contains the device drivers and the XAPI toolstack, and handles I/O on behalf of the guest VMs. See XCP-ng.

  • domU / guest: Any unprivileged domain, in other words a regular virtual machine running your applications, as opposed to dom0. See XCP-ng.

  • HA (High Availability): A pool feature that automatically restarts VMs on the surviving hosts when a host fails. It requires shared storage. See XCP-ng.

  • Host: A physical server running XCP-ng. Every host belongs to a pool, even if it is a pool of one. See XCP-ng.

  • Live migration: Moving a running VM from one host to another (or its disks from one storage repository to another) without downtime.

  • PIF/VIF: A PIF (physical interface) is a physical network card on a host; a VIF (virtual interface) is a virtual network card attached to a VM. See XCP-ng.

  • Pool: A group of up to 64 XCP-ng hosts sharing compute, network, and storage configuration, managed as a single unit. See XCP-ng.

  • Pool master: The host that holds the pool's XAPI database and coordinates the other members. Clients such as Xen Orchestra only need to connect to the master, even in a multi-host pool. See XCP-ng.

  • Remote (backup): In Xen Orchestra, a storage location (such as an NFS or SMB share, or S3-compatible object storage) where backup files are written. See the Xen Orchestra backup documentation.

  • Rolling Pool Update (RPU): A one-click Xen Orchestra feature that updates a whole pool without service interruption: it live migrates the VMs, then updates and reboots each host in turn. See the XCP-ng updates documentation.

  • Snapshot: A point-in-time capture of a VM's disks (and optionally its memory) that you can revert to later. Snapshots are also the base mechanism of Xen Orchestra backups. See Xen Orchestra.

  • SR (Storage Repository): The storage container that holds virtual disks (VDIs). An SR can be local to a host or shared across a pool (NFS, iSCSI, Fibre Channel, XOSTOR). See XCP-ng.

  • Template: A VM model (operating system settings, virtual hardware, install source) used to create new VMs. XCP-ng ships with templates for common operating systems, and you can convert your own VMs into templates.

  • Tiebreaker/witness: A third component that two-node storage or HA solutions use to keep quorum: when the two nodes lose sight of each other, it decides which side keeps running. See TwinStor for a two-host solution designed to work without a dedicated witness node.

  • VDI (Virtual Disk Image): A virtual disk stored on an SR and attached to a VM. See XCP-ng.

  • XAPI: The Xen API toolstack that manages XCP-ng hosts. It runs in dom0 on every host, and all clients (Xen Orchestra, XO Lite, the xe CLI) talk to the pool through it. See XCP-ng.

  • XCP-ng: The open source virtualization platform based on the Xen hypervisor, and the hypervisor layer of Vates VMS. See XCP-ng.

  • Xen: The open source type-1 hypervisor at the core of XCP-ng. It runs directly on the hardware and hosts the domains (dom0 and the guest VMs). See XCP-ng.

  • Xen Orchestra: The web-based management solution for XCP-ng: infrastructure administration, backup, monitoring, and automation in one central interface. See Xen Orchestra.

  • XO Lite: A lightweight version of Xen Orchestra served directly by your XCP-ng host: it runs entirely in your browser, with nothing to deploy, for single-pool administration. See XO Lite.

  • XO Proxy: A component you deploy close to a remote site or a large infrastructure to carry backup data streams locally, while the main XOA keeps orchestrating the jobs. See XO Proxy.

  • XOA (Xen Orchestra Appliance): The prebuilt, ready-to-use virtual machine that runs Xen Orchestra, maintained and supported by Vates. See Xen Orchestra.

  • XOSTOR: The hyperconverged storage solution for XCP-ng: it replicates the local disks of your hosts into a shared Storage Repository, with no external storage hardware. See XOSTOR.