Problem
A NAS snapshot schedule retains too many large media changes, consuming the space that the creator assumed was free for new footage.
Solution
Root Cause / Diagnostic:
ZFS/Btrfs snapshots freeze file blocks at the moment of capture. When editors delete or overwrite massive raw media files or render caches, the deleted blocks are not freed back to the storage pool because they remain referenced by active historical snapshots, silently consuming terabytes of expected free capacity.
Actionable Fix:
1. Snapshot Retention Policy Pruning: Revise the snapshot lifecycle policy to exclude high-churn directories (such as render scratch and proxy folders) and expire media snapshots after 7–14 days.
2. Orphaned Snapshot Destruction: Manually identify and destroy historical snapshots holding large deleted media datasets using `zfs list -t snapshot -o name,used,refer -s used`.
3. Space Reclamation Verification: Run `zpool list` to verify that freed blocks are reclaimed and available storage capacity reflects true physical availability.
Pro Tip:
Deleting a 2TB footage folder won't free up any space on your NAS if you have snapshots enabled; make sure to exclude render scratch folders from snapshots so your storage doesn't quietly fill up.
ZFS/Btrfs snapshots freeze file blocks at the moment of capture. When editors delete or overwrite massive raw media files or render caches, the deleted blocks are not freed back to the storage pool because they remain referenced by active historical snapshots, silently consuming terabytes of expected free capacity.
Actionable Fix:
1. Snapshot Retention Policy Pruning: Revise the snapshot lifecycle policy to exclude high-churn directories (such as render scratch and proxy folders) and expire media snapshots after 7–14 days.
2. Orphaned Snapshot Destruction: Manually identify and destroy historical snapshots holding large deleted media datasets using `zfs list -t snapshot -o name,used,refer -s used`.
3. Space Reclamation Verification: Run `zpool list` to verify that freed blocks are reclaimed and available storage capacity reflects true physical availability.
Pro Tip:
Deleting a 2TB footage folder won't free up any space on your NAS if you have snapshots enabled; make sure to exclude render scratch folders from snapshots so your storage doesn't quietly fill up.