autovacuum disk IO - Mailing list pgsql-admin

I've noticed that autovac. process worked more than 10 minutes, during this zabbix logged more than 90% IO disk utilization on db volume....

===========>29237   2016-03-02 15:17:23 EET 00000 [24-1]LOG:  automatic vacuum of table "lb_upr.public._reference32": index scans: 1pages: 0 removed, 263307 remaintuples: 298 removed, 1944753 remain, 0 are dead but not yet removablebuffer usage: 67814 hits, 265465 misses, 15647 dirtiedavg read rate: 3.183 MB/s, avg write rate: 0.188 MB/ssystem usage: CPU 5.34s/6.27u sec elapsed 651.57 sec

Is it possible to log autovac. io impact during it execution?

Is there any way to limit or "nice" autovac. process?

Thanks to all for any help.