The LaCie 5big 5TB Spare Network Internal Hard Drive is for use with Lacie 5big network storage systems. This drive's 3.5" form factor allows it to easily fit into your 5big storage bays. To access and transfer data this drive's disk spins at a speed of 5400RPM's. This drive also features 32MB's of cache for recalling frequently used bits of data. The Lacie 5TB 5big spare drive is secured RAID compatible, allowing it to seamlessly share data between multiple drives and automatically rebuild RAID mode when replacing a failed drive. When swapping a Lacie 5big drive it is necessary to choose a drive with equal or higher capacity than the disk that's being replaced.