OWC SoftRAID 5

Five RAID Levels for All Purposes
Choose from five RAID levels to accommodate all types of hard drive usage: RAID 0, 1, 4, 5, and 1+0. Store your data super securely, access it lightning fast, or opt for a combination of speed and security.

Protect Your Data with SoftRAID RAID Volumes
Standard hardware RAID products only protect you from file loss during hard drive failures. SoftRAID goes further by constantly monitoring your drives and warning you in advance—before a drive fails—so you have time to replace faulty drives and recover valuable files and data.

Not only do you have the assurance of being alerted to hard drive issues, but with SoftRAID, you can continue working even if a drive fails.

You can check your disks at any time to ensure that all sectors are readable. SoftRAID's Validate Volumes checks readability and parity, while Certify Disk ensures that a disk is readable before you store your work on it (Note: Certifying your disk will erase all data stored on it).

Now Including SMART over USB
SoftRAID tests your SATA drives for SMART errors and can use SMART data to predict drive failures for USB and FireWire drives.
SoftRAID Monitor with Notifications

The SoftRAID Monitor runs continuously, even when you are not logged into your Mac. It monitors your disks and volumes for errors and alerts you as soon as a problem occurs. It can even send you an email.

The SoftRAID Monitor can also predict when a hard drive failure is imminent. Most drives exhibit internal errors one or two weeks before failure. The SoftRAID Monitor looks for these errors and warns you when a drive is having issues and is likely to fail.