Snapshot Generation: Forest vs Lotus
Forest plays an important role in timely, efficient network snapshot generation: while it is possible to generate a snapshot with Lotus, doing so is significantly slower and more expensive. On a regular machine, Forest completes a basic chain snapshot export much faster than Lotus, and with a fraction of the memory.
Both implementations produce compatible snapshots and can consume snapshots produced by the other.
Lotus snapshots are not compressed by default; Forest compresses them as part of the export. Both implementations can consume compressed snapshots. Compressing a Lotus snapshot after generation is possible but adds further to the total time.
Forest snapshots (.forest.car.zst) also embed an index that lets Forest use the file directly as a read-only blockstore, serving blocks in place without importing them into a database. The index is stored in skippable frames, so Lotus and other tools can still read the snapshot; they just ignore the index. Reading a snapshot in place this way is currently Forest-only.