On 2020-09-09 15:53, Brad Campbell via Dng wrote:
> On 5/9/20 10:38 pm, Simon Walter wrote:
>> On 9/5/20 12:50 PM, Gregory Nowak wrote:
>>> On Sat, Sep 05, 2020 at 12:26:21PM +0900, Simon Walter wrote:
>>>> Reallocation, to my knowledge, should happen in the background. It's
>>>> *possible* that the reallocation event and the FS corruption are
>>>> unrelated.
>>>
>>> My understanding is that the drive won't attempt to reallocate a
>>> sector until that sector is written to. So, if the e2fsck -f did try
>>> to write to that sector, the drive did reallocate it in the
>>> background. I do stand to be corrected as always.
>>>
>>
>> Interesting. I think reallocation also happens as part of SMART self
>> checks and reads.
>
> It really doesn't. It'll mark a sector as "pending" (as in, I can't read
> from it so I'll mark it for later).

What does the OS get at this point? Is that a short read error?

...
>
> I have drives that have > 70,000h on them with one or two reallocated
> sectors. I've also had drives grow them at a rapid rate. SMART isn't all
> that good at actually predicting pending failure.

I hope I didn't make it sound like that. SMART does not include
prediction. It's just data, and it needs be interpreted. I should have
probably said that I have never had a drive fail without being warned by
my monitoring system (which includes logging SMART data).

Best regards,

Simon