Hallo again,

here are some other logs that might be connected to the failure:

[...]
Jul  2 17:52:25 speicher48 kernel: [17690.334458] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.338722] sd 10:0:20:0: [sdx] Device not ready
Jul  2 17:52:25 speicher48 kernel: [17690.338723] sd 10:0:20:0: [sdx] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jul  2 17:52:25 speicher48 kernel: [17690.338726] sd 10:0:20:0: [sdx] Sense Key : Not Ready [current] 
Jul  2 17:52:25 speicher48 kernel: [17690.338728] sd 10:0:20:0: [sdx] Add. Sense: Logical unit failed self-configuration
Jul  2 17:52:25 speicher48 kernel: [17690.338731] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 00 00 00 00 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.342955] sd 10:0:20:0: [sdx] Device not ready
Jul  2 17:52:25 speicher48 kernel: [17690.342956] sd 10:0:20:0: [sdx] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jul  2 17:52:25 speicher48 kernel: [17690.342959] sd 10:0:20:0: [sdx] Sense Key : Not Ready [current] 
Jul  2 17:52:25 speicher48 kernel: [17690.342961] sd 10:0:20:0: [sdx] Add. Sense: Logical unit failed self-configuration
Jul  2 17:52:25 speicher48 kernel: [17690.342964] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 00 00 10 00 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.374555] sd 10:0:20:0: [sdx] Device not ready
Jul  2 17:52:25 speicher48 kernel: [17690.374562] sd 10:0:20:0: [sdx] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jul  2 17:52:25 speicher48 kernel: [17690.374569] sd 10:0:20:0: [sdx] Sense Key : Not Ready [current] 
Jul  2 17:52:25 speicher48 kernel: [17690.374577] sd 10:0:20:0: [sdx] Add. Sense: Logical unit failed self-configuration
Jul  2 17:52:25 speicher48 kernel: [17690.374587] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 22 ee c0 80 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.379051] sd 10:0:20:0: [sdx] Device not ready
Jul  2 17:52:25 speicher48 kernel: [17690.379055] sd 10:0:20:0: [sdx] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jul  2 17:52:25 speicher48 kernel: [17690.379061] sd 10:0:20:0: [sdx] Sense Key : Not Ready [current] 
Jul  2 17:52:25 speicher48 kernel: [17690.379068] sd 10:0:20:0: [sdx] Add. Sense: Logical unit failed self-configuration
Jul  2 17:52:25 speicher48 kernel: [17690.379076] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 22 ee c0 80 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.383570] sd 10:0:20:0: [sdx] Device not ready
Jul  2 17:52:25 speicher48 kernel: [17690.383575] sd 10:0:20:0: [sdx] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jul  2 17:52:25 speicher48 kernel: [17690.383581] sd 10:0:20:0: [sdx] Sense Key : Not Ready [current] 
Jul  2 17:52:25 speicher48 kernel: [17690.383588] sd 10:0:20:0: [sdx] Add. Sense: Logical unit failed self-configuration
Jul  2 17:52:25 speicher48 kernel: [17690.383597] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 22 ee c1 20 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.388115] sd 10:0:20:0: [sdx] Device not ready
Jul  2 17:52:25 speicher48 kernel: [17690.388120] sd 10:0:20:0: [sdx] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jul  2 17:52:25 speicher48 kernel: [17690.388126] sd 10:0:20:0: [sdx] Sense Key : Not Ready [current] 
Jul  2 17:52:25 speicher48 kernel: [17690.388133] sd 10:0:20:0: [sdx] Add. Sense: Logical unit failed self-configuration
Jul  2 17:52:25 speicher48 kernel: [17690.388141] sd 10:0:20:0: [sdx] CDB: Read(10): 28 00 22 ee c1 20 00 00 08 00
Jul  2 17:52:25 speicher48 kernel: [17690.392689] sd 10:0:20:0: [sdx] Device not ready
[...]

after this sdx was fallen out of md2

Thanks
Lars