I upgraded one of my drives recently (disk 8) and I was having trouble getting it to rebuild, it kept getting errors and then the rebuild would pause. If I tried to resume it it would disable the disk and just start a parity check.

I didn't have much data on it so while it was being emulated I was able to move all the data off and remove the drive from the array then I re-added the drive as a new drive and was able to successfully rebuild the parity.

Recently I had a power outage and an unclean shutdown and the drive has failed again and I am getting the same errors. I have tried using both the existing drive and a hot spare I had pre cleared and both failed with the same errors.

I am trying to figure out if I just got unlucky with 2 bad drives or if there is another issue causing it.

Any help would be greatly appreciated.

unraid-diagnostics-20250625-1623.zip

Disk dropped offline, this is typically a power/connection issue, and SMART looks OK, recommend replacing both cables and trying again.

Thanks, I'm currently away from the server so I'll attempt this fix when I return and update the thread

I have swapped over the cable used for the drive and attempted a rebuild still having the same issues.

i have attached another diag.

unraid-diagnostics-20250630-0808.zip

Both power and SATA cables?

It's one cable powering 5 drives and the 2 drives that are failing are on 2 different power cables, I have ordered a new hba to test if that is the issue

Was finally abel to do some more work on this, its currently been rebuilding for several hours.

The issue seems to be overloading a rail on the power supply with to many HDD's got another cable to even the load out a bit more and it seems to be working.

Thanks for all the help.