From: Gionatan Danti <g.danti@assyoma.it>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org, g.danti@assyoma.it
Subject: Re: Disabling barriers on NVC-backed HDD
Date: Wed, 15 Nov 2017 19:53:52 +0100 [thread overview]
Message-ID: <434c9f876ca7fe93664419600e2e33a6@assyoma.it> (raw)
In-Reply-To: <20171115173100.GD5119@magnolia>
Il 15-11-2017 18:31 Darrick J. Wong ha scritto:
>
> I would evaluate these drives to find out if you really /can/ yank the
> power without losing anything.
If I can get some hard drives for testing, I'll surely do that. However,
any in-house testing inevitably has limited scope and it can miss some
important failure modes, so I am interested in other users' first-hand
experience.
> That said, if the manufacturers aren't willing to tell you how that
> feature works, I'd just as soon pretend the feature didn't exist and
> continue sending flushes to the drive.
From a point, I agree: I do not like black boxes. On the other hand,
hardware RAID controllers *are* black boxes, and we all use them...
> FWIW if the drive really /does/ have a non-volatile WC then a flush
> should have nearly zero overhead. (Or so you'd think...)
From my understanding (and I can be wrong), these drives honour cache
flushes, with the associated performance drop.
Ok, too much conjectures from my side, I think. I should *really* get my
hand on some of these drives...
Regards.
--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
GPG public key ID: FF5F32A8
next prev parent reply other threads:[~2017-11-15 18:53 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-15 17:01 Disabling barriers on NVC-backed HDD Gionatan Danti
2017-11-15 17:31 ` Darrick J. Wong
2017-11-15 18:53 ` Gionatan Danti [this message]
2017-11-15 19:47 ` Christoph Hellwig
2017-11-15 20:17 ` Gionatan Danti
2017-11-15 20:18 ` Gionatan Danti
2017-11-15 20:27 ` Gionatan Danti
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