JorgeB

Please post output of: fdisk -l /dev/sdb

It's the esiest way, you can also assign them to the array, without parity and do a read check.

Strange, what Unraid release? Try to get the syslog: cp /var/log/syslog /boot/syslog.txt

I don't know what you changed, best to reset to default.

Are you doing it in the Interface rules? Doesn't look like it since it requires a reboot.

That suggests a hardware problem, start with memtest, you can also try another power supply if available.

Because of this, also very usual for SSDs to have pending sectors or "surface" errors, they usually work or don't work.

No, this is because the array is unprotected if a disk fails. XFS has a large overhead.

Yep.

How are you doing that? It must be done on Settings -> Network Settings -> Interface Rules (reboot required)

Try to get the diags by typing "diagnostics" in the console.

Don't need to change anything in the BIOS, you don't even need a BIOS.

Probably, but you'd need to find out the chip used. Mellanox Connectx-X 2 and 3 are cheap on Ebay and work great.

If you're using any Antivirus/firewall make to try with those disable and it's been known to cause issues before.

Also, you shouldn't preclear SSDs.

You can use the diskspeed docker.

For cheaper RJ45 options look for an Aquantia based NIC, e.g. Asus XG-C100C, or an used Intel one.

If it's not needed yes, don't use it, I once had issues with a SATA controller because of that.

No, Unraid uses serial number, just make sure it's a regular HBA, don't use RAID controllers.

There are several compatible NICs, do you want SFP+ or RJ45?

If it's an SSD run blkdiscard: blkdiscard /dev/sdX

This step doesn't exist, just start the array with parity2 unassigned so Unraid can "forget" it, then stop array and you can use it to replace the disable disk, good idea to at least check SMART for all disks before getting rid of it though.

It needs to be re-synced.

No, unless the existing drive was also cleared and never formatted.

Cache device dropped offline: Oct 22 19:43:47 HRH-UNRAID kernel: ata4: limiting SATA link speed to 3.0 Gbps Oct 22 19:43:47 HRH-UNRAID kernel: ata4: hard resetting link Oct 22 19:43:52 HRH-UNRAID kernel: ata4: softreset failed (1st FIS failed) Oct 22 19:43:52 HRH-UNRAID kernel: ata4: reset failed, giving up Oct 22 19:43:52 HRH-UNRAID kernel: ata4.00: disabled Oct 22 19:43:52 HRH-UNRAID kernel: ata4: EH complete Oct 22 19:43:52 HRH-UNRAID kernel: sd 4:0:0:0: [sdb] tag#7 UNKNOWN(0x2003) Result: hostbyte=0x04 driverbyte=0x00 Oct 22 19:43:52 HRH-UNRAID kernel: sd 4:0:0:0: [sdb] tag#7 CDB: opcode=0x2a 2a 00 06 fa 92 80 00 06 00 00 Oct 22 19:43:52 HRH-UNRAID kernel: print_req_error: I/O error, dev sdb, sector 117084800 Check connections.