I wonder, that there is so much discussion about harddrives. I use a few WD Caviar green 24/7 without any problems after deactivating the default idle timer, which kills the drive with a journaling filesystem. But I take care, what you wrote and bought a 24/7 hd for a DS112j (still in order process), a Hitachi Deskstar 5K3000 HDS5C3020ALA632 since it has less power consumption with 5400rpm. The HDS723020BLA642 with 7200rpm is listed.
Can you imagine any problems with a Hitachi Deskstar 5K3000 HDS5C3020ALA632 ? It is listed at http://forum.synology.com/wiki/index.php/User_Reported_Compatible_Hard_Drives but not at http://www.synology.com/support/hd.php?lang=deu&bays_id=1&product_id=101
Can you imagine any problems with a Hitachi Deskstar 5K3000 HDS5C3020ALA632 ? It is listed at http://forum.synology.com/wiki/index.php/User_Reported_Compatible_Hard_Drives but not at http://www.synology.com/support/hd.php?lang=deu&bays_id=1&product_id=101