vfs.zfs.write_to_degraded missing in 10.1?

[Gabor Radnai]

Hi,

I run 10.1-stable (r281854), is it possible I missed the announcement of
removing vfs.zfs.write_to_degraded sysctl variable?

The Handbook's Advanced Topics 20.6 is mentioning this variable as "to
allow writing to degraded vdevs to prevent the amount of free space across
the vdevs from becoming unbalanced, which will reduce read and write
performance."

How can this be achieved currently?

Thanks.