It is the cache (NOT battery-backed, so dangerous to start with) and is likely related to the drives not being compatible. Either 1) it is using some onboard cache, or 2) (more likely) it is using the drive cache for the writeback, for either of which the drives' timings and response capability would become important. I would use them with no cache or in non-RAID (and mirror in the OS). Mirroring in the OS will give you far superior performance and reliability as well.
Hi, I am having a major problem with my machine: I am creating a RAID 1 via the Intel RST Windows Software on Windows 10 (latest Intel software and driver release from their website). The creation and initalization is succeeding just fine and I can format the the volume afterwards and the Windows Explorer displays the volume accordingly. Problem: When I start copying files to that particular RAID 1 volume the process is starting and continuing up to a certain undefinded point. Then the transfer rate drops to 0 bytes/sec suddenly and that's it. I can not copy anything anymore after that, I have to cancel the transfer and the volume can't be accessed anymore via Explorer. The next thing that happened was that the Intel RST was showing that the RAID1 was degraded because of the HDD connected to port 0. I deleted the RAID via Ctrl+I before booting and performed an extended SMART test - the drive was fine. Anyway I decided to have the HDD (WD Red 2 TB) exchanged by Western Digital. Yesterday the replacement arrived and I created an entirely fresh RAID1. I tried to copy a few files and after a certain time the transfer rate dropped to 0 again and the RAID can't be accessed anymore. I am beginning to assume that the mainboard has an issue. Do you have any clue or thinking what could help my problem? Thanks in advance, Jay.  EDIT: My system is the PowerEdge T30 running the 1.0.5 BIOS and the OS in installed on a SATA SSD. There are two WD Red 2TB drives for the RAID1 and a single WD Red 8 TB that will store data just like that.
Massive problem with Intel RST Raid 1 // PowerEdge T30