On Sun, Mar 28, 2021 at 6:51 PM Tim via users users@lists.fedoraproject.org wrote:
I'm recently seeing info like this in logwatch emails:
**Unmatched Entries** Device: /dev/sda [SAT], CHECK POWER STATUS spins up disk (0x81 -> 0xff)Which makes little sense to me. The system is a 24/7 server, not often rebooted. It's a solid state drive, and I don't know what the hex that means (pun intended). I've no idea if that's an error, or if it's just telling me that drive has changed modes (idle/active).
I'm not sure. The smartmontools folks probably know. They have a mailing list. Ask them and let us know?
Logically I'd expect that if SMART thought the drive might need checking or chucking, it'd start to give me useful warnings ahead of time, and I might be lucky enough to backup my files before disaster struck. But the warnings ain't that useful. And, of course, it's entirely possible for a drive to spontaneously fail before any scheduled SMART test took place.
The trend seems to be it can be semi-useful for HDD. The pending sectors and seek errors going up quickly is a pretty good warning something is going wrong.
For SSDs, your first indication for prefail is often checksum errors, at least in Btrfs land. Either it returns garbage or zeros. It seems the drive itself is not likely to report an uncorrectable read or write error like you'd get on HDD. And the next level of failure for SSD is it goes read-only. Not the file system, the drive - and this too is totally silent in my handful of experiences with this failure mode, happily accepts all write command without error but none of them are persistent. Another mode of SSD failure that's common is, it just vanishes off the bus. Does not say bye! It just goes bye!