Under the section where you reactivate an ost on the client side it looks lie there is a typo...

the entry given is as follows:
client# lctl set_param osc.fsname-OSTnumber-*.active=0

Which is the same entry from 14.8.3 where you deactivate the ost on the client side:
[client]# lctl set_param osc.fsname-OSTnumber-*.active=0

Shouldn't it be active=1 to reactivate?