Choosing the right backup method
Nimbus Backup is built on Proxmox Backup Server (PBS). Depending on your environment, there are three entry points into Nimbus: Proxmox VE, the Nimbus Backup Gateway or NimbusBackupClient. This guide helps you pick the right one.
Proxmox VE
Recommended if you already run Proxmox VE
Nimbus Backup Gateway
Recommended for any non-Proxmox system
NimbusBackupClient
Open source — one Windows host to any PBS
Method 1 — Proxmox VE
Recommended if you already run Proxmox VE. This is the most direct path: Proxmox Backup Server integrates natively with your hypervisor. No intermediary, no agent to deploy.
Method 2 — Nimbus Backup Gateway
Recommended for any non-Proxmox system. The Gateway is a multi-protocol ingestion gateway: your NAS, Linux servers and business software back up as usual, then Nimbus protects everything to PBS. It protects one or several NAS, behaves as a target you push your data to (« like a NAS »), and can even ingest OneDrive exports with a little configuration. Commercial offering, standard protocols, optional MSP services on top.
Use cases
NAS
Synology, QNAP, TrueNAS, Unraid — via Hyper Backup, HBS 3, rsync, SMB, NFS, WebDAV or S3.
Linux
Scheduled rsync jobs, SQL/PostgreSQL dumps, application archives and exports.
Business software
ERP, DMS, accounting or production software exporting over FTP, SFTP, SMB or NFS.
S3-compatible
Object backups, application exports and archiving: point your S3 client at the Gateway.
Supported ingestion protocols
Which protocol for your source (Synology, QNAP, TrueNAS, Linux, Windows…) and which one preserves native versioning? See the backup protocols matrix.
Worked example — Synology
Your NAS keeps using Hyper Backup normally. The backup travels over a dedicated VPN to the Gateway, then Nimbus replicates it to the Main PBS and, optionally, to PBS AirGap.
The NAS keeps its habits; Nimbus handles protection and retention.
Method 3 — NimbusBackupClient
An open-source project that lets Windows use Proxmox Backup Server. It is the open-source alternative to the Gateway for the Windows world, but on the opposite model: NimbusBackupClient installs as an agent on the host and pushes to PBS, whereas the Nimbus Backup Gateway behaves as a NAS-style target you drop your backups onto. The agent is free but unwarranted; the Gateway is managed and SLA-backed. The client's edge: it works with any Proxmox Backup Server (not just Nimbus) and is ideal for a single host.
Important — this is not a commercial product
NimbusBackupClient is not a commercial Nimbus Backup product. It is provided without SLA, without warranty and without any support commitment. For a supported, committed service, prefer the Proxmox VE method or the Gateway.
Comparison of the three methods
A quick read to place each method against your target system and support needs.
| 1 · Proxmox VE | 2 · Gateway | 3 · NimbusBackupClient | |
|---|---|---|---|
| Target system | Proxmox VE (VMs, containers) | 1 or several NAS, Linux, business software, S3, OneDrive | Windows (single host) |
| Support / operated by Nimbus | Yes (managed PBS plans) | Yes (Cloud, managed Appliance) | No — community project |
| SLA | Yes, depending on PBS plan | Yes, depending on Gateway plan | No SLA |
| Commercial product | Yes | Yes | No (open source, no warranty) |
| PBS compatibility | Nimbus PBS | Nimbus PBS | Any PBS (not just Nimbus) |
| Learn more | Offsite Proxmox → | Gateway hub → | GitHub → |
One source, several PBS
Whatever the ingestion method, a single source can be protected by several Proxmox Backup Servers. You compose the level of redundancy based on the PBS plan you subscribe to.
PBS France
Datacenter in France for sovereignty and network proximity.
PBS Europe
Geographically distinct secondary copy for resilience.
PBS AirGap
Network-disconnected copy to resist ransomware.
All plans are detailed on the PBS plans page. For the anti-disaster multi-site logic, see the field report on the OVH Strasbourg fire.
Air-gap and long-term archiving
Beyond multi-PBS replication, Nimbus can replicate your backups to a PBS AirGap, to LTO tape or to a secure vault — depending on the plan you subscribe to.
PBS AirGap
Disconnected copy, sheltered from a network compromise.
LTO tape
Long-term cold archiving, disconnected by nature.
Secure vault
Physical retention of media in a safe location.
Sizing your backup: RPO, RTO and the 3-2-1-1-0 rule
Picking an ingestion method is not enough: you also need to define how much data you can afford to lose (RPO), how quickly you must be back up (RTO) and how many copies you keep. These three parameters dictate the PBS plan and the level of air-gap to aim for. To turn your volume and bandwidth into concrete durations, estimate your backup window and how long the first backup will take.
Field proof — first PBS backup of a 1 TB Windows server
On a 1 TB Windows server, the first PBS backup transferred 876 GB in 20h30, with 75% deduplicated chunks and 57% end-to-end savings. Block-level deduplication sharply reduces the volume actually stored, which directly affects how you size your retention. Read the case study →
RPO or RTO: what is the difference?
The RPO (Recovery Point Objective) is the maximum amount of data you accept to lose, expressed in time: a 24-hour RPO means that, at worst, you lose one day of data. The RTO (Recovery Time Objective) is the maximum acceptable time to restore service after an incident. The RPO is driven by how often you back up; the RTO is driven by the restore method and the network link.
RPO — data lost
"How much data can I lose?" Driven by backup frequency: the higher it is, the shorter the RPO.
RTO — recovery time
"How fast must I be back up?" Driven by the restore method and the throughput of the link to PBS.
From 3-2-1 to 3-2-1-1-0
The 3-2-1 rule calls for 3 copies of your data, on 2 different media types, with 1 kept off-site. The 3-2-1-1-0 rule hardens it: +1 immutable or air-gapped copy, and 0 errors — meaning backups that are verified and actually restored, not merely scheduled. This is the standard a modern offsite backup aims for against ransomware.
Immutable, air-gap and WORM: three levels of protection
These three notions are often confused, but they form a clear hierarchy: logical immutability < physical air-gap < WORM medium. Each one guards against an additional risk.
Immutable (logical)
A backup locked against modification/deletion during retention (software lock, append-only). Protects from ransomware, but stays connected.
Air-gap (physical)
Physical isolation: the medium is connected to nothing. Ransomware cannot reach what is plugged in nowhere. Stronger than logical immutability.
WORM (medium)
Write Once Read Many: written data can no longer be rewritten (LTO tape in WORM mode, locked object). Immutability etched into the medium itself.
What is an immutable backup?
An immutable backup is a backup that can be neither modified nor deleted during a defined retention period. It is a logical immutability (software lock, append-only mode): it protects against ransomware that tries to encrypt or wipe backups, but the copy stays connected and reachable on the network. It is strong protection, but it does not replace a disconnected copy.
Is a second NAS enough as an air-gap?
No: a second NAS on the same site and the same network is not an air-gap. It shares the same exposure to physical disaster (fire, water damage, theft) and to ransomware, which spreads across the local network. A true air-gap requires physical isolation — a disconnected medium, ideally off-site — that nothing on the network can reach.
These three levels, at Nimbus
Nimbus combines all three: PBS immutability protects every backup, the PBS AirGap (optional) adds a physically disconnected copy, and archiving to LTO tape in a vault provides a WORM medium. You step up protection according to the plan you subscribe to, from a simple logical lock to write-once media.
Frequently asked questions
Not sure which method to choose?
We review your environment, identify the right entry point into Nimbus and send you a clear quote. A 15-minute tech call, no strings attached.