ahrens commented on this pull request.
> @@ -1039,6 +1039,13 @@ metaslab_group_allocatable(metaslab_group_t *mg,
> metaslab_group_t *rotor,
if (mg->mg_no_free_space)
return (B_FALSE);
+ /*
+ * Relax allocation throttling for ditto blocks. Due to
+ * random imbalances in allocation it tends to push copies
+ * to one vdev, that looks a bit better at the moment.
+ */
+ qmax = qmax * (4 + d) / 4;
I found this math a little hard to follow. Maybe this would be more clear:
```
// increase qmax by 1/4 for the 2nd DVA, and by 1/2 for the 3rd dva
qmax += qmax * d / 4;
```
How did you decide on 1/4 (as opposed to 1/8, or 10, or unlimited)?
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