Re: [PATCH 05/13] lightnvm: pblk: Count all read errors in stats

Javier González
2019-03-04T11:45:29Z

[-- Attachment #1: Type: text/plain, Size: 1861 bytes --]

> On 4 Mar 2019, at 12.41, Hans Holmberg <hans@owltronix.com> wrote:
>
> On Mon, Mar 4, 2019 at 10:23 AM Javier González <javier@javigon.com> wrote:
>>> On 4 Mar 2019, at 10.02, Hans Holmberg <hans.ml.holmberg@owltronix.com> wrote:
>>>
>>> Igor: Have you seen this happening in real life?
>>>
>>> I think it would be better to count all expected errors and put them
>>> in the right bucket (without spamming dmesg). If we need a new bucket
>>> for i.e. vendor-specific-errors, let's do that instead.
>>>
>>> Someone wiser than me told me that every error print in the log is a
>>> potential customer call.
>>>
>>> Javier: Yeah, I think S.M.A.R.T is the way to deliver this
>>> information. Why can't we let the drives expose this info and remove
>>> this from pblk? What's blocking that?
>>
>> Until now the spec. We added some new log information in Denali exactly
>> for this. But since pblk supports OCSSD 1.2 and 2.0 I think it is needed to
>> have it here, at least for debugging.
>
> Why add it to the spec? Why not use whatever everyone else is using?
>
> https://en.wikipedia.org/wiki/S.M.A.R.T. :
> "S.M.A.R.T. (Self-Monitoring, Analysis and Reporting Technology; often
> written as SMART) is a monitoring system included in computer hard
> disk drives (HDDs), solid-state drives (SSDs),[1] and eMMC drives. Its
> primary function is to detect and report various indicators of drive
> reliability with the intent of anticipating imminent hardware
> failures."
> Sounds like what we want here.

I know what smart is… You need to define the fields. Maybe you want to
read Denali again - the extensions are couple with smart.

> For debugging, a trace point or something(i.e. BPF) would be a better
> solution that would not impact hot-path performance.

Cool. Look forward to the patches ;)

Javier

[-- Attachment #2: Message signed with OpenPGP --]
[-- Type: application/pgp-signature, Size: 833 bytes --]