From: Gionatan Danti <g.danti@assyoma.it>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Darrick J. Wong" <darrick.wong@oracle.com>,
linux-xfs@vger.kernel.org, g.danti@assyoma.it
Subject: Re: Disabling barriers on NVC-backed HDD
Date: Wed, 15 Nov 2017 21:18:31 +0100 [thread overview]
Message-ID: <e7d6cada4330c02c86e5159ef987c0d9@assyoma.it> (raw)
In-Reply-To: <442aa3b110e7cf10c8920dfe2159e41f@assyoma.it>
Il 15-11-2017 21:17 Gionatan Danti ha scritto:
> Il 15-11-2017 20:47 Christoph Hellwig ha scritto:
>> And in that case it will report WCE=0 and Linux won't even flush.
>> As is the case for typical enterprise disks.
>
> Good point. Based on what I read here[1], page n.4, it *seems* that
> Seagate AWC (advanced write cache) enabled drives report WCD (write
> cache disabled) to the host OS.
>
> I think this is the key parameter to watch: if the HDD vendor is
> confident enough to report WCE=0/WCD, than it should be safe running
> without barriers (after all, in this case Linux *will* disable barrier
> by default).
>
> Thank you Christoph for pointing that.
> Regards.
Sorry, I forgot the link:
https://www.seagate.com/files/www-content/product-content/enterprise-performance-savvio-fam/enterprise-performance-15k-hdd/_cross-product/_shared/doc/enchanced-cache-advantage-tp691.1-1610us.pdf
--
Danti Gionatan
Supporto Tecnico
Assyoma S.r.l. - www.assyoma.it
email: g.danti@assyoma.it - info@assyoma.it
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next prev parent reply other threads:[~2017-11-15 20:18 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
2017-11-15 19:47 ` Christoph Hellwig
2017-11-15 20:17 ` Gionatan Danti
2017-11-15 20:18 ` Gionatan Danti [this message]
2017-11-15 20:27 ` Gionatan Danti
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