It's been some months since any activity on this post... so I'm not sure if anyone is still checking, or if the latest status is more promising.
I'm having the same problem as reported in this post by Candyman, also with the Seagate ST31500341AS 1,5TB Drives (firmware CC1H) on the DS408, configured as a RAID5 array of 3x1.5Tb.
One of the disks would report read errors and drop out of the RAID5 array, anywhere from after a day up to a week.
Even after replacing the initial "failed" disk (Seagate support responded the CC1H firmware was correct), the same problem with a disk dropping out of the RAID array happened again within a week. Actually, the disk not only dropped from the RAID array, but the DS408 Web UI reported the disk was not connected to the NAS - sometimes after a reboot of the DS408 it would show again.
In the meantime I plugged the failed disk into a PC and ran the Seagate utility "Seatools for Windows" to check for faults, but none were reported.
So far, 3 of the 4 Seagate 1.5Tb disks have dropped out of the RAID5 array after the DS408 reports many read errors for that disk (in the system logs).
After some investigations I found the procedure on the Synology site, which details how to correctly prepare disks for RAID, and I started to follow this (http://forum.synology.com/wiki/index.php/How_to_prepare_a_Hard_Disk_whilst_installed_in_a_Synology_NAS
). Unfortunately, during this process, another disk dropped out of the RAID array and the volume went to status "Crashed", consequently losing all data on the volume. Interestingly the 2nd disk that failed had already been through the disk preparation process and was previously successfully used to rebuild the RAID5 array.
I'm not sure if the problem is related to the DS408, or the Seagate 1.5Tb disks. I also read on this forum (http://forum.synology.com/enu/viewtopic.php?p=59755&sid=cbb21c6932bae10a89e2e0d6ca213f42#p60057
) multiple people reported that faulty SATA cables were provided with the NAS, causing similar issues. Surely 3 of the 4 SATA cables provided aren't faulty in my DS408... I can't fail the Seagates on thier own so have no valid reason to return them.
Has anyone had a stable system running using these Seagate 1.5Tb drives in RAID5 on a Synology NAS? Or even non RAID?
I've spent so much time and money on this, along with some lost data, I feel I've bought a real dud, either the DS408 or the Seagate disks... it hasn't served it's purpose at all and has only been a counter-productive exercise so far.
Thanks in advance for any reply...