You use the disk previously used to establish RAID5, in order to ensure the correctness of the data, Intel Rapid Storage driver is being initialized RAID5 (the length of time depends on the size of your capacity, if it is 2T is estimated to be 5-8 hours), indeed, Intel Rapid Storage Write speed is very slow, after the opening of the cache can be done after the small block of data 100-200M / s, but the large block of data is not improved. After turning on the cache, the small data block can be 100-200M/s, but the big data block is not improved, after all, "Intel Rapid Storage" RAID5 is not hard but soft, so it's very slow.