Technical reference

Glossary infrastructure & virtualisation

Definitions of technical terms encountered in enterprise infrastructure projects, VMware migration and Proxmox VE.

Backup

PBS: Proxmox Backup Server. Backup solution dedicated to Proxmox VMs and containers. Uses deduplication and compression to reduce disk space. Comparable to Veeam in the open-source ecosystem.

Cluster

Corosync: Inter-node communication daemon in a Linux cluster. Used by Proxmox VE and Pacemaker to synchronise cluster state and detect host failures.
Pacemaker: Cluster resource manager. Decides which VMs to start/migrate on failure, using Corosync for failure detection.

Container

LXC: Linux Containers. Lightweight containerisation technology built into Proxmox VE. Less isolated than a VM, LXC shares the host kernel and consumes fewer resources.

Hypervisor

ESXi: VMware (now Broadcom) type-1 hypervisor. Proprietary kernel optimised for virtualisation, replaced in open-source contexts by KVM/Proxmox.
KVM: Kernel-based Virtual Machine. Linux kernel module that turns Linux into a type-1 (bare-metal) hypervisor. Technological base of Proxmox VE, direct competitor to VMware ESXi.
Proxmox VE: Open-source virtualisation platform based on KVM and LXC. Proxmox Virtual Environment includes a web UI, HA cluster management, VM replication and native integration with Ceph and PBS.

Migration

OVF / OVA: Open Virtualization Format. Standard VM packaging format portable between hypervisors. OVA = OVF archive + disks. Proxmox can import OVAs exported from VMware.
V2V: Virtual-to-Virtual. Conversion of a VM from one format/hypervisor to another. Common tools: virt-v2v (Red Hat), OVA import, or manual conversion via virsh/qemu-img.

Network

SDN: Software-Defined Networking. In Proxmox VE, the SDN module allows defining VXLAN, EVPN and network zones directly from the web UI. Open-source alternative to NSX.
VXLAN: Virtual Extensible LAN. Network encapsulation protocol (RFC 7348) for creating L2 overlay networks over L3 infrastructure. Used by NSX and Proxmox SDN.

Operations

Snapshot: Point-in-time VM state capture. Used for incremental backups (PBS) and pre-migration restore points. Proxmox supports RAM snapshots (with memory state) and disk-only snapshots.

Performance

IOPS: Input/Output Operations Per Second. Storage performance metric. Ceph NVMe can reach 100k+ IOPS/node on flash; traditional SAN solutions are typically limited by FC network latency.

Resilience

DRP: Disaster Recovery Plan. Set of procedures for restoring a system after a disaster. Different from HA (real-time): DRP targets a contractually defined RTO/RPO.
HA (High Availability): Automatic VM restart on a healthy node if a host fails. Proxmox HA uses Corosync + Pacemaker for cluster coordination.
RPO: Recovery Point Objective. Maximum acceptable data loss, expressed in time. Defines the minimum backup frequency.
RTO: Recovery Time Objective. Maximum acceptable downtime duration. Key DRP indicator: defines the time between failure and activity resumption.

Storage

Ceph: Open-source distributed storage system. Provides block (RBD), object (S3-compatible) and file (CephFS) storage. Native integration in Proxmox VE for shared storage without SAN.
Ceph RBD: RADOS Block Device. Ceph block interface used by Proxmox to store VM disks. Supports snapshots, clones and thin provisioning.
DRBD: Distributed Replicated Block Device. Synchronous block replication between two Linux nodes. Historically used for HA without SAN. Proxmox supports DRBD via drbd-utils plugin, but Ceph is recommended for new deployments.
NFS: Network File System. Network file sharing protocol supported by Proxmox as a datastore. Simple but less performant than Ceph RBD or iSCSI for I/O-intensive workloads.
SAN: Storage Area Network. Dedicated storage network (FC, iSCSI, NVMe-oF). Proxmox supports iSCSI and FC via LVM storage plugins. Replaceable by Ceph to reduce proprietary hardware dependency.
Thin provisioning: Dynamic storage allocation. A thin-provisioned 100 GB disk only occupies the space actually used. Proxmox, Ceph and ZFS natively support thin provisioning.
ZFS: Advanced filesystem and volume manager. Natively integrated into Proxmox VE: handles snapshots, checksums, compression and software RAID (RAIDZ). Local alternative to Ceph for small clusters.

VMware

DRS: Distributed Resource Scheduler. Automatic load balancer in a vSphere cluster. Proxmox has no native automatic equivalent — balancing is manual or scripted.
NSX: VMware Software-Defined Networking layer. Manages microsegmentation, VXLAN and distributed routing. Open-source equivalent: OVN/OpenSDN.
Storage vMotion: Live storage migration of a VM between VMware datastores. Proxmox supports live storage migration for VMs with Ceph disks.
vCenter: Central VMware management platform. Orchestrates vSphere clusters, vMotion, DRS and HA. Sold separately by Broadcom since the 2023 VMware acquisition.
vMotion: Live VM migration between ESXi hosts without service interruption. Proxmox equivalent: live migration via KVM/QEMU (requires shared storage — Ceph or NFS).
vSAN: VMware hyperconverged storage solution. Creates a distributed datastore from local ESXi host disks. Open-source equivalent: Ceph RBD on Proxmox.
vSphere: VMware virtualisation suite comprising ESXi and vCenter. De facto enterprise standard until the Broadcom acquisition and pricing restructure.

Vendor

Broadcom: Semiconductor company that acquired VMware in late 2023 for $61 billion. Restructured VMware pricing from a per-CPU to a per-core model, with significant increases for mid-market enterprises.

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