Power supply underpowered for Rockpro64, deficient PCIe SATA card, or something else?

[daffy]

Hi! I have a Rockpro64 NAS-- I bought just about everything listed on the wiki for the setup (https://wiki.pine64.org/wiki/NASCase).

I use two 3.5" Hitachi HDDs connected via the PCIe SATA adapter (bought from Pine store) for my data drive (I use only 1 drive actively-- the other is for backup-- not RAID). The OS (Armbian 21.05.1 Buster with Linux 4.4.213-rockchip64 with OMV) runs on eMMC. The unit, including the 2 internal HDDs, runs on the 12V 5A power supply I bought from Pine store. The HDDs are powered with the "custom power cable" that came with the Pine NAS box.

Every time I try to copy large files (a few hundred MB and larger) to the data HDD in my NAS server, the transfer fails and the filesystem drops to read-only.

Thinking that it could be drive failure, I have cloned (with clonezilla) the data drive two times to try other (new) HDDs but the problem persists. So, this isn't a drive failure issue.

On top of this, when I copy large files to an external HDD with its own power supply that is attached to the NAS via USB (of course, this isn't using the SATA card either since it's using USB), the transfer works perfectly and does not fail.

So, one possibility is that I am not getting enough power to the internal HDDs, which causes the copy to fail and the filesystem to drop to read-only. I have tried different circuits in my house (U.S. so 120V) thinking that maybe one circuit is overtaxed, but I still have the same problem.

I have seen in some other threads (e.g. https://forum.pine64.org/showthread.php?tid=9079) that some folks have not been happy with the PCIe SATA adapter that is offered in the Pine store. Anybody have thoughts on this?

Or does anyone have any other suggestions on what my problem could be?

Can you please advise on what I can do to fix this problem? Do I need to buy a beefier power supply or a different PCIe SATA card?

Thanks in advance.