The definitions are illustrated as follows (PG stands for placement group):
OSD 40 OSD 33
+-------------------------+ +-------------------------+
| shard 0 - PG 10 | | shard 1 - PG 10 |
|+------ object O -------+| |+------ object O -------+|
||+---------------------+|| ||+---------------------+||
stripe||| chunk 0 ||| ||| chunk 1 ||| ...
0 ||| stripe 0 ||| ||| stripe 0 |||
||+---------------------+|| ||+---------------------+||
||+---------------------+|| ||+---------------------+||
stripe||| chunk 0 ||| ||| chunk 1 ||| ...
1 ||| stripe 1 ||| ||| stripe 1 |||
||+---------------------+|| ||+---------------------+||
||+---------------------+|| ||+---------------------+||
stripe||| chunk 0 ||| ||| chunk 1 ||| ...
2 ||| stripe 2 ||| ||| stripe 2 |||
||+---------------------+|| ||+---------------------+||
|+-----------------------+| |+-----------------------+|
| ... | | ... |
+-------------------------+ +-------------------------+