Racking up a second RackMac mini Xserver provides two redundant metadata controllers occupying a total of just 2U of rackspace and costing a fraction of available alternatives.
To achieve equal performance on a write IOPS basis utilizing hard disk drives would require over 400 drives, 36U of rackspace and consume more than 300 times the power.
In addition, the "A-Drive" can be extended for enterprise storage applications, reducing power consumption by up to 50%, resulting in greener and more efficient data centres with better optimisation of the already limited rackspace.