how to locate a bad HDD in a NAS or server QNAP?

The two disks from the original RAID1 show ERROR ...one or more unrecoverable read/write errors have been detected. SMART says everything is good.

If formatting (no matter if using Windows or Linux) fixes the I/O error, it would be by 'retiring' defect sectors. All HDD have some 'spare' ...

I tried doing a bad block scan and try to delete the I/O error history, but now the NAS detects bad blocks, when no bad blocks were found while ...

1 – Your External HDD may got bad sectors. Please be sure your external HDD doesnt give error on your Windows Pc. Also please install Seagate Seatools software.

我剛migrate 去新NAS 時，都出現這問題(WD RED 3TB), 之後用WD 個software 做1次full write zero (約20hrs) , 結果沒有發現任何問題。

結論就是：把Toshiba硬碟全部移除，只留HGST的硬碟，就再也沒有出現，有回報給QNAP客服，不過，Toshiba的硬碟的型號MD03ACA300V還在官網的相容性清單裡面。

I tried doing a bad block scan and try to delete the I/O error history, but now the NAS detects bad blocks, when no bad blocks were found while ...

It sounds like a sector on the drive is iffy, and has hit the point where the signal processing on the drive can't read the data, and this has ...