Backup of CAD and BIM projects: strategies for an architectural studio

Loss of an ongoing project is one of the worst possible events for an architectural studio, months of work, dozens of inspections and communication with the client in a single file that can be permanently saved to a disk which fails the very next day. Backing up CAD and BIM data has its own rules, as it differs significantly from backing up standard office documents.

Why CAD and BIM projects pose a specific risk

Architectural studio project files have three characteristics that complicate standard backup procedures: they are large (a central model of a residential building can easily be hundreds of megabytes to single-digit gigabytes), they change frequently and simultaneously from multiple workstations, and their value increases with the time spent working on them. Losing a file on a Friday afternoon before submission causes significantly greater damage than losing the same file at the start of the project.

The 3-2-1 rule: the foundation to build on

The 3-2-1 rule is a proven standard that covers most real-world failure scenarios:

• 3 data copies - original working file plus two backups
• 2 different media - for example, a NAS in the office and an external hard drive or cloud storage, not two copies on the same type of device.
• 1 copy off-site - backup stored off-site to protect it from fire, flooding or theft together with the original

We have described in detail the selection of a shared storage solution for studios in our article. on choosing a NAS for an architectural studio - A NAS with snapshots typically forms the first two layers of this rule, with an off-site copy completing the third.

What belongs in the backup

Backing up only the project file is not enough. The studio should also regularly back up:

Version retention: how much history do you really need?

Backup and versioning are not the same. Backup protects against data loss; versioning protects against an error that has entered the data and gone unnoticed for some time: typically a deleted element, a corrupted central model or an accidentally overwritten version. Recommended retention for an architectural studio:

For large projects, it is worthwhile to keep a copy as of the date of each key delivery to the client or authority, in case of disputes or additional changes, the studio needs to return to it even after months.

Automation: a backup that requires no thought.

Backups that rely on someone in the team remembering to perform them will fail sooner or later. A functional setup has three characteristics:

• Runs automatically according to schedule, outside working hours, so as not to slow down the synchronization of central models
• Reports failures - email notification or alert in the team tool if a backup fails, not just a silent log that no one monitors.
• Is checked regularly - a monthly quick check is sufficient to confirm that the last backup has run and is of appropriate size

Recovery after an incident: what RPO and RTO mean in practice

Two concepts determine how good a backup strategy is in a crisis. RPO (recovery point objective) states how much work the studio can lose at most, with daily backups, this is up to one working day. RTO (recovery time objective) states how long it takes to restore operations, with NAS snapshots this is often minutes, while recovery from an off-site cloud backup takes hours to days depending on data volume and connection speed.

We recommend performing a test restoration at least once or twice a year: take a backed-up project, open it on another workstation and verify that it is complete and functional. This is the only reliable way to confirm that the backup process actually does what it should.