Ata Error In Messages File

Does anyone know what the following events in /var/log/messages mean. It looks like some sort of failure on the ata bus. Does the last line mean that it successfully wrote all data using the cache, or could there be data loss?

The output of smartctl looks ok for the disk.

Code:
Jul 26 16:44:35 server1 kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x2 frozen
Jul 26 16:44:35 server1 kernel: ata1.00: cmd c8/00:08:9d:e2:8a/00:00:00:00:00/ec tag 0 cdb 0x0 data 4096 in
Jul 26 16:44:35 server1 kernel: res 40/00:01:00:4f:c2/00:00:00:00:00/00 Emask 0x4 (timeout)
Jul 26 16:44:42 server1 kernel: ata1: port is slow to respond, please be patient (Status 0xd0)
Jul 26 16:45:05 server1 kernel: ata1: port failed to respond (30 secs, Status 0xd0)
Jul 26 16:45:05 server1 kernel: ata1: soft resetting port
Jul 26 16:45:10 server1 kernel: ata1.00: revalidation failed (errno=-2)
Jul 26 16:45:10 server1 kernel: ata1: failed to recover some devices, retrying in 5 secs
Jul 26 16:45:15 server1 kernel: ata1: soft resetting port
Jul 26 16:45:15 server1 kernel: ata1.00: configured for UDMA/133
Jul 26 16:45:15 server1 kernel: ata1: EH complete
Jul 26 16:45:15 server1 kernel: SCSI device sda: 976773168 512-byte hdwr sectors (500108 MB)
Jul 26 16:45:15 server1 kernel: SCSI device sda: drive cache: write back