8.1.1 went GA today - decided to stage it on our DR 2240

Its rolling through some disk firmware updates now - how disruptive are these ?  Will they add Disk IO when I upgrade my prod clusters?
If its doing a raid group reconstruction for each, how are they so quick? (aggr1 is 5Tb)

Fri Aug 24 13:52:15 PDT [dr-na-01:raid.rg.recons.start:debug]: /aggr0/plex0/rg0: starting reconstruction, using disk 0a.00.3  
Fri Aug 24 13:52:15 PDT [dr-na-01:raid.rg.recons.done:debug]: /aggr0/plex0/rg0: reconstruction completed for 0a.00.3 in 0:00.10  
Fri Aug 24 13:54:15 PDT [dr-na-01:bdfu.selected:info]: Disk 0a.00.5 [NETAPP   X421_HCOBD450A10 NA01] S/N [PNHAL1TY] selected for background disk firmware update.  
Fri Aug 24 13:54:40 PDT [dr-na-01:raid.rg.recons.start:debug]: /aggr0/plex0/rg0: starting reconstruction, using disk 0a.00.5  
Fri Aug 24 13:54:40 PDT [dr-na-01:raid.rg.recons.done:debug]: /aggr0/plex0/rg0: reconstruction completed for 0a.00.5 in 0:00.09  
Fri Aug 24 13:56:40 PDT [dr-na-01:bdfu.selected:info]: Disk 0a.00.8 [NETAPP   X421_HCOBD450A10 NA01] S/N [PNJZAM5Y] selected for background disk firmware update.  
Fri Aug 24 13:57:04 PDT [dr-na-01:raid.rg.recons.start:debug]: /aggr1/plex0/rg0: starting reconstruction, using disk 0a.00.8  
Fri Aug 24 13:57:04 PDT [dr-na-01:raid.rg.recons.done:debug]: /aggr1/plex0/rg0: reconstruction completed for 0a.00.8 in 0:00.11  
Fri Aug 24 14:01:05 PDT [dr-na-01:bdfu.selected:info]: Disk 0a.00.10 [NETAPP   X421_HCOBD450A10 NA01] S/N [PNJY7BPY] selected for background disk firmware update.  
Fri Aug 24 14:01:29 PDT [dr-na-01:raid.rg.recons.start:debug]: /aggr1/plex0/rg0: starting reconstruction, using disk 0a.00.10  
Fri Aug 24 14:01:29 PDT [dr-na-01:raid.rg.recons.done:debug]: /aggr1/plex0/rg0: reconstruction completed for 0a.00.10 in 0:00.14  
Fri Aug 24 14:03:29 PDT [dr-na-01:bdfu.selected:info]: Disk 0a.00.9 [NETAPP   X421_HCOBD450A10 NA01] S/N [PNHG1SSB] selected for background disk firmware update.  
Fri Aug 24 14:03:54 PDT [dr-na-01:raid.rg.recons.start:debug]: /aggr1/plex0/rg0: starting reconstruction, using disk 0a.00.9  
Fri Aug 24 14:03:54 PDT [dr-na-01:raid.rg.recons.done:debug]: /aggr1/plex0/rg0: reconstruction completed for 0a.00.9 in 0:00.07  

thanks

Fletcher