4 ms·
Hard drives lie. SMART data is not thorough and it is not trustworthy. Across dozens of drive failures over the years, I've never seen SMART predict a failure b
by ianhowson 6y ago
Hard drives lie. SMART data is not thorough and it is not trustworthy. Across dozens of drive failures over the years, I've never seen SMART predict a failure before ZFS detected data loss or the OS reported 'drive is slow'. SMART is not worth the effort to monitor.
Filesystems don't read SMART data. You might have a separate daemon which monitors SMART.
ZFS checksumming is amazing for this. You know, without doubt, which file(s) are bad. You can still use failing or unknown quality drives because the checksumming will protect you from silent data corruption.
- toast0 6y agoSMART marking drives as failed is usually super late. But if you monitor the raw values for the important parameters (unreadable, reallocated, etc sectors), I've had good luck with replacing drives before software notices. At least for spinning drives; SSD failues were way more rare, but resulted in the drives completely disappearing from the bus, and no reliable prefail indicators. I did have one SSD go through a big reallocation that tanked throughput and the alerts from throughput and the alerts from SMART thresholds fired simultaneously. Of course, that's great for a server farm; in home use monitoring is a lot less structured.
- pixl97 6y agoExpensive enterprise drives are generally better at smart stats. Of course your mileage varies by vendor. Desktop drives on the other hand are completely untrustworthy.