Re: [PATCH v2] nvme: enable FDP support

["Martin K. Petersen" <martin.petersen@oracle.com>]

Hi Keith!

> One thing FDP got right was mandating the Endurance Log: the drive
> must provide a feedback mechanism for the host to know if what they're
> doing is helpful or harmful.

Good luck teaching firefox what to do with that information!

> If you're just blindly throwing random fcntl hints, then you're not
> the target audience for the feature; you're expected to iterate and
> tweak your usage.

And that's exactly my point. What the various attempts at data
management in the specs have in common is that they are unsuitable for a
general purpose operating system and its applications.

We can all come up with a restrictive model which works beautifully for
one particular application. No problem. But that's not what standards
are supposed to be about! We used to produce specifications which worked
for every type of application and device.

It was a beautiful thing when we went away from cylinders, heads, and
sectors as tools to do performance management on storage. An abstracted
model for managing blocks that has worked for everything from USB flash
drives, over spinning rust, to million dollar storage arrays. With one
protocol. For decades. And still going. Because the abstraction worked,
and it removed the burden of having to care about device implementation
artifacts from applications and operating systems alike.

We need a similar model for data management. Something which works well
enough on the device media management side but which transcends one
particular application or device implementation. I really don't believe
any of the currently defined data management schemes are timeless the
same way as LBAs have proven to be...

-- 
Martin K. Petersen	Oracle Linux Engineering