File systems expert for a news article (urgent)

Warner Losh imp at
Sun May 1 17:04:06 CDT 2016

Host-aware SMR doesn't require changes, but will benefit from them The host
can optimize
where things are placed and the order it does things, but otherwise needs
no changes. And
even if you don't change things, it will still work, but maybe with really
bad performance.

Host-managed SMR does require file system changes. It forces filesystems to
be almost
a pure log since most of the modifiable blocks need to be written in
'strips' rather
than randomly.

Drive-managed SMR doesn't require any changes, and hosts can't take
of the stripe geometries because they aren't communicated to the host, nor
the current details that a host-aware or host-managed host can use.


On Sat, Apr 30, 2016 at 11:56 PM, Alex McWhirter <alexmcwhirter at>

> Sounds like some of the SMR stuff Seagate is working on. Not sure if HAMR
> needs fs changes or not, but I know SMR does for certain.
> Sent from my T-Mobile 4G LTE Device
> -------- Original message --------
> From: Eric Christopherson <echristopherson at>
> Date: 5/1/2016  1:44 AM  (GMT-05:00)
> To: "General Discussion: On-Topic and Off-Topic Posts" <
> cctalk at>
> Subject: Re: File systems expert for a news article (urgent)
> On Fri, Apr 29, 2016, Evan Koblentz wrote:
> > >>Anyone here on cctalk consider themselves a file systems expert and
> have
> > >>the credentials or job title to vouch for it? If so, then I need to
> > >>interview you ASAP today (in the next hour-ish) for a
> > >>article. Contact me offline: news at
> > >>
> > >>Not going to discuss the story itself here in public.
> > >>
> > >
> > >Can you be a little more specific?  File systems is quite broad
> > >
> >
> > One of the hard disk standards bodies is working on a new feature (which
> I'm
> > not going to post here) that would require changes to file systems,
> > otherwise the new feature is academic and useless in the real world. So
> I am
> > looking for someone with FS chops to comment on whether the changes can
> > reasonably happen. Cannot say more except in private.
> Hopefully not something that would require said filesystem
> implementators to pay licensing fees or sign NDAs or take affirmative
> action to limit users' use of data, or onerous things like that.
> --
>         Eric Christopherson

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