Design Prometheus recovery beyond a single local data directory

Long retention on one disk is different from replicated and recoverable monitoring history.

Source facts

Prometheus documents that its local storage is neither clustered nor replicated and should be managed like another single-node database. It recommends snapshots for backups. Its storage guidance cautions against unsupported non-POSIX filesystems and states that NFS filesystems are unsupported. If time- and size-based retention policies are both specified, whichever triggers first is used.

Source: Prometheus documentation — Storage.

Applicability

Review Prometheus local TSDB backup, supported filesystem and local retention policy.

DSE recommendation

DSE recommends defining the acceptable history loss and restoration time before selecting storage and retention. Keep a supported snapshot-based backup procedure and an inventory of configuration, rules, and credentials needed to rebuild the service. Leave space for ongoing ingestion and storage maintenance rather than allocating the entire disk to retained blocks. Do not present a mounted shared filesystem as replication without checking the documented storage requirements. Protect the restore path from the same failure that could destroy the active node.

Verification

In a nonproduction recovery exercise, restore an approved snapshot and required configuration to a separate instance. Verify representative historical queries and current collection after the restore. Record the actual recovery boundary and any missing interval rather than claiming retention duration alone proves resilience. Retain snapshot identity, restored time coverage and the destination filesystem with the result. Have the monitoring owner approve the observed missing interval and recovery time separately from the configured local retention target.

Official reference

Prometheus documentation — Storage. Reviewed October 20, 2026.