I'm not sure if the board needs to go down at all.
It does depend on how they do it, i should have said in my original post
"When they do the backup it is possible they may shut your board down for a few minutes"
instead of
"When they do the backup it is normal for the board to be shut down for the duration"
It will probably go on without you even noticing, but if they do shut you down for 1 min or 1 hour at least you will be fore-warned...............
If they just have to extract your Sql Database from their complete forums database then you wont notice it.