There is no single best zarr chunk size for reading the Herculaneum scrolls. On one region of Scroll 1, re-chunked five ways and read three ways, read amplification ranged from 1.3× to 176× — same bytes, only the chunk geometry and access pattern changed. I measured it on a laptop, and put the missing chunk cache back on the Python reader while I was there.

Jul 21, 2026