In plain words
Sizing a backup is like planning a storage unit. The first move takes a long time and fills a lot of space; after that, each week you only bring what has changed. The size of the unit depends on what you keep (yesterday's boxes, last week's, last year's), and the round-trip time depends on the road: a corridor for a USB drive, a motorway for the local network, a country lane for the internet.
Choosing the destination
| Destination | Protection against ransomware | Off site | Restore speed | Good to know |
|---|---|---|---|---|
| USB drive | Only if it is unplugged after each backup | If you take it away (rotate two drives) | Fast | Simple and subscription-free, but relies on a human habit |
| NAS on the local network | Weak if permanently mounted; good with immutable snapshots | No | Fast | Use a dedicated account and never a share mounted on workstations |
| Dedicated Linux server | Good in append-only mode (rest-server, Borg) or as a hardened repository (Veeam) | If remote | Fast locally | The most solid on-site solution |
| S3 object storage | Very good with Object Lock | Yes | Limited by internet download speed | Ideal for the off-site copy, to seed with a drive for large volumes |
The right combination is almost always one local copy to restore quickly, and one off-site, immutable copy to survive the worst.
Choosing the tool
| Tool | Licence | Platforms | Strengths | Limits |
|---|---|---|---|---|
| Restic | Open source | Linux, Windows, macOS | Deduplication, encryption, native S3, a single executable | Command line; pruning a large remote repository is slow |
| BorgBackup | Open source | Linux, macOS | Very efficient, append-only mode over SSH | No object storage; no native Windows version |
| Kopia | Open source | Linux, Windows, macOS | Graphical interface, S3 with object locking, automatic maintenance | Less common in businesses |
| Proxmox Backup Server | Open source (optional support subscription) | Proxmox VE machines, Linux servers | Incremental virtual machine backups, deduplication, verification | Designed for the Proxmox ecosystem |
| Veeam Agent | Proprietary, free edition | Windows, Linux, macOS | Full workstation backup, bare-metal restore | Free: a single job, no long-term retention, no direct object storage |
| Veeam Backup & Replication | Proprietary, free Community Edition up to 10 machines | VMware, Hyper-V, Proxmox VE, agents | Immutable hardened repository, copies, instant recovery | Licence beyond 10 machines; Windows server or Linux appliance |
How the tool calculates
- Space starts from one full backup, adds the changed data kept by the retention, applies the compression and deduplication saving for the type of data, then one year of growth and 20% free space.
- With deduplication (Restic, Borg, Kopia, Proxmox Backup Server), a monthly backup only costs the blocks that changed since the previous one. The tool assumes changes are concentrated on part of the data (files in progress, databases), about five times the daily rate: changing 2% of the data every day mostly touches the same 10%.
- With Veeam, the full backups of long-term retention only cost the changed blocks on an XFS or ReFS repository (fast clone) or on object storage. On a USB drive or a NAS, each one takes its full size.
- Durations use realistic throughputs: about 110 MB/s for a 1 Gb/s network, 150 MB/s for a USB hard disk, and 85% of the internet bandwidth.
A backup is only as good as its restore
Restore a file every quarter and a whole machine every year, and write down the result. That is the "0" in the 3-2-1-1-0 rule: zero errors on restore. See the 3-2-1 backup rule, the tutorial Backing up a Linux server with restic and the tutorial Veeam: backing up workstations and servers.