Rebuild your RAID while Apple Data Recovery rescues your data
Despite the built-in redundancy and active fail over capability of most RAID architectures, data loss is still very possible. When a RAID array fails, it's important to remember it is the data that is valuable - the hardware is can be replaced quickly and affordably while a data recovery specialist retrieves your lost data from the affected drives.
It is important to understand why and what should be done during an array failure, particularly a multi-disk failure. If only one drive fails, the array will continue to allow read and write access to the data, but if a second drive were to fail on 5 drive system, then all the data on the array could potentially be lost.
Multiple-drive failures do happen and can be caused by component quality issues, recent firmware changes or by environmental factors such as heat and vibration, power surges. If the array develops a problem, do not assume that you will be able to fix it yourself. Hoping the problem will clear up by repeatedly resetting or power-cycling the array can make the problem worse.
Any failed drives must be replaced immediately, but since the array will appear to be working normally, this can easily be overlooked. Until the faulty drive is replaced and the array rebuilt, all the data on the array is potentially vulnerable to a second drive failure. If the RAID set is quickly removed and handed to a specialist, they will have a better chance of successfully recovering the data. New drives can be installed and the applications are likely to be back on line with less delay.