how much free space do you need to have on drobo before you can turn on the dual disk redundancy option?
OBVIOUSLY it would be at least another 1 x your largest disk just for capacity reasons, but that would give you a drobo 100 %full - so can you only turn the option on if you would have say at least 15% free AFTER You turn on the option?
8 x 1TB drives - single redundancy give 7TB available for data (im going to ignore the stupid round for the sake of this example)
now obviously you need another 1TB disk for the dual disk redundancy, so it is physically impossible to turn it on if you have more than 6TB of data on there
if you did have 6TB exactly and were able to turn it on (you are not) then the resultant 2 disk redundancy disk pack would be 1005 full which Drobo wouldnt be happy with.
so is it that you cant turn on dual disk redundancy if the resultant pack would give a capacity warning ?
i am guestimating that you must have less than 85% of the dual redundancy disk pack’s capacity’s worth of data?
so in my example the 8TB drobo with single disk redundancy, can only be converted to dual disk redundancy if you have less than 5.1TB of data on it (85% of the 6TB available in dual redundancy mode?)
oddly i cant find this documented anywhere, hopefully jennifer can give us the official answer as to what capacity the “dual redundancy” check box becomes available - my drobo is stuffed and im taking data off it to put it back to dual disk redundancy)