Hi,

Looking for some help as I'm out of my wits.

My array configuration

4TB*4 HDD (3 disks+1 Parity)

2TB*2 HDD

2*512GB SATA SSDs

I got an error on one of the 2TB drives and it was disabled (It was a WD Blue drive if that matters).

I ran a smart short test and it passed. I then tried rebuilding the disk on itself.

Stopped Array

Removed error disk.

Started Array in Maintenance mode.

Stopped Array

Added the disk back

Started Array in maintenance mode.

Sync

While it started rebuild, it was REALLY slow ( less than 1 MB/s)

I assumed the disk was actually gone so I replaced it with a new 4TB WD Red Plus drive.

With the new disk, I tried rebuild again.

Same problem, build speed less than 1 MB/s.

Next I thought it might be the SATA cable. So I replaced the cable.

Next rebuild, same speed. Even got some read errors on the new disk and rebuild failed.

I then removed all the power and SATA cables.

Replugged all drives again.

Started sync and it started okay with typical 150 MB/s speed.

But after ~5 minutes, it's back to less than 1 MB/s.

Attaching diagnostics while the sync is running.

Do let me know if more information is needed.

Any help is appreciated.

PS: I'm using a PCIe to SATA card for attaching 3 drives. 5 are attached to the Motherboard.

Thank You.

atom-diagnostics-20250925-1411.zip

Constant ATA errors for disk4, replace its cables and try again.

18 hours ago, JorgeB said:

Constant ATA errors for disk4, replace its cables and try again.

Thank You.
Seems it was a faulty power cable/connector for disk4.