Somit ist heute Abend wieder Harddisktausch angesagt.The results of the analysis of the logs is quite clear: the drive with the ID 0 (S/N: WD-WCAW3ETT0ASR) is failing with read- and write-errors. The RAID card is having difficulties to establish a proper communication with this right after the start of the system. Either there's a cabling issue or the drive is simply failing. I recommend to replace that drive and to check, if the RAID configuration becomes stable again. The ID 0 has got the data transfer rate of 3 Gbps. Because the drive started to fail the RAID card lowered the data transfer rate to 3 Gbps attempting to stabilize the communication. All the other drives in the present configuration do not have any indication of a failure.