Blogs›Dropbox›Magic Pocket Storage Efficiency
Dropbox's Magic Pocket, an immutable blob store, faced increased storage overhead due to fragmentation caused by a new service that led to severely under-filled volumes. The existing L1 compaction strategy was insufficient to reclaim space efficiently from these sparse volumes. To address this, Dropbox developed a multi-strategy approach, including improvements to steady-state compaction and new methods for cleaning up the sparsest volumes, aiming to reduce overhead below previous baselines. This post details how Dropbox reduced its monorepo size from 87GB to 20GB by identifying and addressing an issue with Git's delta compression heuristic, which was inefficiently packing internationalization files due to their directory structure. By working with GitHub to implement a more aggressive repack strategy with tuned parameters, they significantly improved clone times and reduced operational risk.
4/2/2026
This post details the incident that led to increased storage overhead in Magic Pocket due to under-filled volumes. It explains the limitations of the existing L1 compaction strategy in handling this scenario and introduces new strategies for reclaiming space from sparse volumes, including a multi-strategy approach to drive overhead down.
3/25/2026
This post details how Dropbox reduced its monorepo size from 87GB to 20GB by identifying and addressing an issue with Git's delta compression heuristic, which was inefficiently packing internationalization files due to their directory structure. By working with GitHub to implement a more aggressive repack strategy with tuned parameters, they significantly improved clone times and reduced operational risk.