Storage tiers

Crumb writes into one broad media root, bind-mounted into both the recorder and the API (read-write for the recorder, read-only for the API). Within that root, footage can live across multiple named storage locations, typically a live tier on fast storage and an archive tier for older footage on larger, cheaper storage, though a single-disk install with no archive tier at all is equally valid.

Adding a disk

Adding storage doesn't require a compose file edit or a restart of the stack's shape. Mount the new disk (or a subdirectory of an existing mount) under the same host media path, then add the corresponding path in the admin console. The recorder creates the necessary subdirectory on its first write there.

How footage moves between tiers

When a policy has an archive tier configured, footage moves there after its live-tier window passes, following a crash-safe sequence: copy, verify the copy (size and checksum), update the database row to point at the new location and stage, then delete the source. A reader only ever sees the old location or the new one, never a half-moved state, and startup reconciliation scans both live and archive storage so an interruption partway through a move gets picked back up rather than leaving orphaned or dangling data behind.

Headroom and spill

Advanced per-policy settings allow a free-space headroom buffer and a spill target, so a policy can be configured to move footage out (or stop accepting new footage on a tier) before a disk actually fills up, rather than only reacting after the fact.