[alex137]

Good.

Now, what is the recommanded layout of the node buffers (the 4MiB buffers). I've read about Packed Memory Arrays, but don't quite get the complete idea. Can we really do better than read, merge, write ?

(A pity there's no preview button on this forum...)

[leif]

Unsorted is fine, we're just counting I/Os, and it takes O(1) I/Os to read or write a buffer regardless of the layout.