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Two-disk external drives have one major benefit over single-bay units; they can be configured in RAID to protect your data from disk failure. LaCie’s 2Big USB 3.0 has a pair of 1TB 3½in hard disks for this very purpose.
You have the choice of using the maximum 2TB of storage, or sacrificing 1TB to ensure your data stays safe by mirroring the contents of both disks. A hardware switch enables each RAID mode: you have to disconnect the external hard drive from your PC and reboot it after using the switch.
LaCie includes a PCI Express card to add a USB3 port to any PC, although this doesn’t fully justify the steep price. Testing in RAID 1 mode, large files were written at 99.5MB/s and read at 144.4MB/s. Both scores are very impressive for an external disk, regardless of RAID mode. Small files were equally rapid, being written at 50.6MB/s and read at 66.2MB/s. Switching to RAID 0 increased both read and write speeds by around 10-15 per cent, but we wouldn’t recommend choosing it over RAID 1 because of the higher risk of losing all your data if a disk fails.
Unfortunately for LaCie, we don’t recommend you buy the 2Big at all as it’s very expensive for the capacity. If data security is more important to you than performance, buy the Synology DiskStation DS211j NAS (around £160) and two 1TB hard disks (£40 each). This will give also you all the benefits of a NAS as well.
