I have recently setup my first Unraid server with 9 (2 parity) array drives and 2 cache drives.

Since I did so Less than two month ago I had drives being disable on three occasions. One time both parity drives were disabled the exact same moment and one time a data drive was disabled (although the content was still accessible when mounting it outside the array). Now one of the parity drives is disabled.

I am of cause slightly annoyed by this because the only fix I found so far is to remove the disk from the array and rebuild onto itself. This takes about 40 h and uses a lot more energy than the server is already using (50W idle is quite high when considering German power prices).

Is there a better way to fix this or a way to prevent it in the first place?

speicher-diagnostics-20250907-1806.zip

Any power splitters involved with your disks?

There are 2 x Molex to 4 SATA cables in use. The crimped plug type not the over molding. Therefore I believe the power is highly unlikely to be the issue.

Edited September 7, 2025Sep 7 by Kai3D

Disk looks fine.

Check connections to all disks, both ends, SATA and power, including splitters. Replace cables if problem persist.

As the problem is intermittent , checking if the problem persists is not feasible (error frequency so far about 4 weeks in between).

As I have access to the drive immediately after it becomes disabled, I'm starting to question if the cables could cause this error.

All drives are mounted decoupled and the case has not been touched since at least 3 weeks (up time).

For the time being, is there anything other than a full rebuild that i can do to fix the issue, specially when a data drive is affected?

Unless the emulated disk is not mounting and/or has filesystem issues we recommend rebuilding, if the disk is OK you could create a new config, but you will then need to do a correcting parity check, and that takes the same time as a rebuild.

17 hours ago, Kai3D said:

I have access to the drive immediately after it becomes disabled

Parity plus all other disks emulate the disabled disk from the parity calculation. That is how you can access its data, and how its data can be rebuilt. The disabled disk is not actually accessed again until rebuilt (unless New Config is used as mentioned).

I have mounted the disabled disk (the one time it was a data disk) separat from the array and all data was available. The same happend the one time I had to fix the file system on one of my disks. Data available but I'm unable to enable the disk and check its contents against the parity. A full disk write instead of a read was required to stop the data from being emulated.

Also related but on a different note, will a parity check with "Write corrections to parity" enabled fix a disabled disk or do I have to remove the disk from array and re add it in order to rebuild.

PS: I think I will buy a different HBA card as my current one only runs at 1.5G instead of 6G speed. The reliability also might benefit from this.

2 hours ago, Kai3D said:

will a parity check with "Write corrections to parity" enabled fix a disabled disk

Nope.

You either rebuild the disabled disk, or New Config and rebuild parity. Those are the only ways to get the array in sync again.

The disk was disabled because a write to it failed. That write, and any subsequent writes to the emulated disk, can be recovered by rebuilding the disk. If instead, you rebuild parity, those writes would be lost.

So, rebuilding the disabled disk is preferred over rebuilding parity.