Switching from a SATA-I to a SATA-II disk (Samsung HM641JI 640 GB) showed incompatibilities between chipset used in laptop and HDD : 1+ time per second, syslog shows SATA trabsfer errors, leading to SATA bus reset et resync. Funny : this only occurs when reading bigger data (1MB+), but write accesses seem OK so far.

Slight hope however : even after 1 RMA, technical support suggests a 2nd RMA of the HDD, arguing that the error code suggests defect HDD PCB

Update : even 3rd disk showed the same error code (AJ36). Data transfer was as low as 30MB/s. Fortunately I could test a Seagate Momentus 7200.4 ST9500420ASG 500GB. Two cool things :

• no more SATA issues, even after trasnfering 10GB (dd if=/dev/sda of=/dev/null was the easiest test for the problem, and works even on non-partitioned devices)
• 95+MB/s transfer rate

Of course this is only a 500G device, but at least it’s working fine with my older laptop (Fujitsu Amilo 1437G)