thanx for answer me.
The all vps is in different datacenter europa and usa.
Yes I know 1000 visitors in 24h for this server is not problem: 0.69 visitors every second, but in reality the visitators can be 500 in same moment, maybe this is reason I make the load balancing and sure never know... some time some datacenter can came down.
I wanna know if the back server can work like front server too.
Thank again for answer :)