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 21:17:13 +0100 [thread overview]
Message-ID: <442aa3b110e7cf10c8920dfe2159e41f@assyoma.it> (raw)
In-Reply-To: <20171115194700.GA6228@infradead.org>
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.
--
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 20:17 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 [this message]
2017-11-15 20:18 ` Gionatan Danti
2017-11-15 20:27 ` Gionatan Danti
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