Software Raid5 falls off. Where to begin?

Question

RAID

Hello.
Available software Raid5 on Windows Server 2019 Standard. Collected through the Disk Management console.
When writing to it from an external device, after a while there is a drop in performance (write speed) and the subsequent disconnection of the disk (in Explorer This computer only shows the drive letter without determining the capacity and the ability to access it.)
Or it is possible that there is no drop in performance, only with loss of access to disk.

Answer 1

Start by looking at the SMART of each physical disk that makes up the array.
Look first at the words reallocated and pending, the numbers in the raw column.
If not zero, then make a backup, and then replace the disk with a new one.
Other possible reasons:
- bad SATA cable (try replacing cables on all drives);
- or a failed SATA port (plug the cable into another port);
- chipset overheating up to SATA controller errors;