The problem seems to be the bad SATA cables shipped with server by Dell. As I mentioned I replaced the cables with a new and the drives are working properly now. The server is working for 3 days without problems. I don't think that the problem could be Western Digital drives because they aren't compatible, it's not serious. Thanks.
Hello, we bought Dell PowerEdge T20 for our organization without HDDs. We bought two hard drives Western Digital Black 2 TB 3,5" (WD2003FZEX-00SRLA0) separately and installed them. After that I created mirror raid via software RAID tool (CTRL+I on boot), installed Windows 10 Pro and everything seems to be OK. But after installation of the OS I dettached one of the drives, start the OS and shut down. Then I attached the 2nd HDD and the system started rebuild. In 1-2 hours I noticed that the HDD lamp stop blinking (the rebuild was finish) restart the PC and noticed missing 2nd HDD. The same scenario happens 2-3 times later. Only when I shut down system and power on again the BIOS recognize the second HDD. I'm wondering what occurs this? Bad SATA cable or incompatible disk drive?
Dell PowerEdge T20 - second hard drive disappears