Disk 2 (originally a 4TB drive) in the array became disabled 2 weeks ago. I replaced the disk with an 8tb drive about a week ago and all seemed well. Decided to upgrade to the latest code last week and that went well also.

However today Disk 2 (the new 8TB drive) is showing disabled again.

I am hoping someone in the Unraid community can shed some light on what is happening.

I have attached diagnostics.

Thank you in advance.

tower-diagnostics-20260826-0811.zip

It's not logged as a disk problem, and SMART looks fine, so it's mostly a power/connection issue. Check/replace cables. Also, any power splitters in use?

JorgeB, Thank you so much for the help.

There are some power splitters, but not with the 5 core disks. I tried reseating the power and data cable at the drive (Drive 2) and also at the LSI controller. There is 1 connector for 4 ports at the controller side, of which Disk 2 is using port 4. I rebooted after that and tried reintroducing the 8TB drive into the array and started a parity rebuild. However, during the rebuild it started showing multiple errors on Disk1, which I believe means possible data corruption. I immediately stopped the rebuild and removed Disk 2, rebooted and started the array with no disk 2. Array came online and it appears as though most of the data on disk 1 is there, although I am not sure. Not sure what I am missing, if anything from disk 2.

I also ordered a replacement cable for the LSI controller, which should be delivered tomorrow, but I am afraid to attempt another parity rebuild for fear of losing more data. I cannot understand how an issue with Drive 2 Could cause errors on Disk 1, as I believe the parity rebuild should be reading from Disk 1, 3,4, & 5 and writing to Disk 2.

Any suggestions? I have been an Unraid user for 15 years and have never had anything close to a complete disaster as this situation.

If you are using power splitters what type are they? A SATA->SATA connector should never be split more than 2 ways or you are likely to encounter power-related issues. A Molex->SATA can typically split up to 4 ways without the same sort of issues.

Post new diags after the new errors

Attached are Diagnostics of the Tower as it sits with no Disk 2 installed.

Should I try to rebuild parity and post diagnostics while Disk 1 is getting errors? Will that cause data corruption?

Or should I replace the cable first before trying to rebuild parity?

tower-diagnostics-20260827-0731.zip

Disk1 errors also look like a power/connection issue; it could also be a bad/weak PSU, it woudl repalce the cbales and/or the PSU and try the rebuild again

I will replace the cables when the new one arrives. I can also remove a few SSD's that are installed but not part of the array. I will attempt rebuild after this is done.

Thx.

2 hours ago, tomjrob said:

Should I try to rebuild parity

Just thought I would clarify the terminology so nobody reading gets confused.

You aren't rebuilding the parity disk, you are rebuilding disk2. Better to say you are rebuilding disk2, or maybe rebuilding from parity. Or maybe rebuilding the array, since the end result of rebuilding disk2 should be to have all of the array back in sync. But only disk2 will be rebuilt.

Yes, That is my understanding also. Thanks for clarifying.

Update: Prior to new cable being delivered, I tried removing (3) SSD's to lighten the load on the power supply. When I rebooted Unraid, Disk5 now showed as being missing, so with Disk2 already needing to be rebuilt, that caused an invalid configuration (I currently have single parity drive). So I decided to shut down and wait for a new power supply which should be delivered Sunday 8/30.

I will update this after installing the new supply. Hopefully Disk5 will be there and I can rebuild Disk2.

Thx for the help.

Update: I finally received the new power supply and installed and all drives returned to normal operation. Initiated rebuild of Disk2 and everything completed normally. Most importantly, no data loss.

A big thank you to JorgeB for jumping in to read the diagnostics and determine it to be likely a cable or power supply issue.

Also thanks to trurl for clarifying the terminology.

The Unraid community never ceases to amaze me.

This issue is closed.