1. I put my drive into standby (either waiting or with hdparm -y /dev/sdc)

2. If I set the standy time to e.g. 12,5 min (hdparm -S 150 /dev/sdc) during it is already in standby, then /var/log/messages gives me:

Jul 6 16:36:18 alone kernel: ata4.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
Jul 6 16:36:18 alone kernel: ata4.00: cmd e3/00:96:00:00:00/00:00:00:00:00/40 tag 0
Jul 6 16:36:18 alone kernel: res 40/00:00:00:00:00/00:00:00:00:00/40 Emask 0x4 (timeout)
Jul 6 16:36:18 alone kernel: ata4.00: status: { DRDY }
Jul 6 16:36:18 alone kernel: ata4: hard resetting link
Jul 6 16:36:20 alone kernel: ata4: SATA link up 3.0 Gbps (SStatus 123 SControl 300)
Jul 6 16:36:20 alone kernel: ata4.00: configured for UDMA/133
Jul 6 16:36:20 alone kernel: ata4: EH complete
Jul 6 16:36:20 alone kernel: sd 3:0:0:0: [sdc] 1465149168 512-byte hardware sectors (750156 MB)
Jul 6 16:36:20 alone kernel: sd 3:0:0:0: [sdc] Write Protect is off
Jul 6 16:36:20 alone kernel: sd 3:0:0:0: [sdc] Mode Sense: 00 3a 00 00
Jul 6 16:36:20 alone kernel: sd 3:0:0:0: [sdc] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA


These sounds like an error, however my drive works normally.
Can someone explain me the system messages?