Match restic repository format to the oldest recovery client

Include the emergency recovery executable in restic repository-format compatibility checks.

Source facts

The restic repository-preparation guide distinguishes repository format from program release. Its documented format version 2 requires restic 0.14.0 or newer and adds compression support; version 1 works with any restic version. Initialization can choose a repository version explicitly, while the latest alias selects the newest supported format. Creating a repository with a newer format therefore needs a client-compatibility decision, including the recovery host that may be used when the normal backup machine is unavailable.

Source: restic — Preparing a New Repository.

Applicability

This applies to restic repository initialization as documented in the stable guide reviewed here. Check the deployed releases before applying the compatibility table to a different future format.

DSE recommendation

DSE recommends inventorying every backup, verification, maintenance, and emergency recovery client before creating a repository or changing format policy. State the minimum required restic release in the recovery instructions and keep an approved executable accessible through the recovery process. Avoid relying on the backup host’s current binary as the only compatibility evidence. Have the owner choose an explicit format where reproducibility is required, and review new defaults during software upgrades rather than assuming they remain unchanged.

Verification

Initialize a disposable repository with the intended format and test access from the oldest approved recovery client. Perform a small backup and restore through that recovery path. Retain the repository-format and client-version pair with the result so later executable upgrades can be evaluated against a known baseline.

Official reference

restic — Preparing a New Repository. Reviewed October 15, 2026.