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Subject: Re: add BIO_NORETRY flag, implement support in ata_da, use in ZFS
 vdev_geom
To: Andriy Gapon <avg@FreeBSD.org>, freebsd-fs@FreeBSD.org,
 freebsd-geom@FreeBSD.org
References: <391f2cc7-0036-06ec-b6c9-e56681114eeb@FreeBSD.org>
From: Julian Elischer <julian@freebsd.org>
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Date: Fri, 29 Dec 2017 13:28:41 +0800
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On 24/11/17 6:30 pm, Andriy Gapon wrote:
> https://reviews.freebsd.org/D13224
>
> Anyone interested is welcome to join the review.
> Thanks.

I see you closed the review.

However don't stop working with that problem..

It's still something that a worth a solution, even if not exactly That 
solution.
Maybe a generic idea through the block IO layer of transaction 
requirements.
We did face this issue in a BSD4.3 variant in 1990 where a single disk 
error
would result in a cascading shockwave of slowdowns that took some time 
to resolve.
The issue even comes up in networking too, especially with realtime video
where "don't bother, we missed the window" comes into play.