Understanding the rationale behind dropping of "block devices"

[Aijaz Baig]

Oh thank you Poul. This would hopefully cover almost everything I need to
know!

On Sun, Jan 22, 2017 at 1:32 PM, Poul-Henning Kamp <phk at freebsd.org> wrote:

> --------
> In message <20170121235131.GF1768 at funkthat.com>, John-Mark Gurney writes:
> >Aijaz Baig wrote this message on Mon, Jan 16, 2017 at 14:19 +0530:
> >> Nevertheless my question still holds. What does 'removing support for
> block
> >> device' mean in this context? Was what I mentioned earlier with regards
> to
> >> my understanding correct? Viz. all disk devices now have a character (or
> >> raw) interface and are no longer served via the "page cache" but rather
> the
> >> "buffer cache". Does that mean all disk accesses are now direct by
> passing
> >> the file system??
> >
> >One of the other reasons block devices were removed was that if there
> >was a write error on the underlying device, there was no way for the
> >writer to know that the write failed.  This could/would lead to corrupted
> >data which is bad.
>
> This paper hopefully answers a lot of the questions:
>
>     https://www.usenix.org/conference/bsdcon02/rethinking-dev-and-devices-
> unix-kernel
>
>
> --
> Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
> phk at FreeBSD.ORG         | TCP/IP since RFC 956
> FreeBSD committer       | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
>



-- 

Best Regards,
Aijaz Baig