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From: "Georg Schönberger" <g.schoenberger@xortex.com>
To: Christoph Hellwig <hch@infradead.org>,
	Martin Steigerwald <martin@lichtvoll.de>
Cc: Jens Axboe <axboe@kernel.dk>,
	Linux FS-Devel <linux-fsdevel@vger.kernel.org>,
	Jeff Moyer <jmoyer@redhat.com>,
	Linux Block mailing list <linux-block@vger.kernel.org>,
	XFS mailing list <xfs@oss.sgi.com>
Subject: Re: XFS and nobarrier with SSDs
Date: Mon, 14 Dec 2015 10:18:54 +0000	[thread overview]
Message-ID: <566E978E.2070502@xortex.com> (raw)
In-Reply-To: <20151214095823.GA30662@infradead.org>

On 2015-12-14 10:58, Christoph Hellwig wrote:
> On Mon, Dec 14, 2015 at 09:38:56AM +0100, Martin Steigerwald wrote:
>> Is it safe to use XFS (or any other filesystem) on enterprise SSDs with Power
>> Loss Protection (PLP), i.e. some capacitor to provide for enough electricity
>> to write out all data in DRAM to flash after a power loss, with a reordering
>> I/O scheduler like CFQ?
> If the device does not need cache flushes it should not report requiring
> flushes, in which case nobarrier will be a noop.
OK - that would also mean that mounting with nobarrier should not make a 
performance difference.

> Or to phrase it
> differently:  If nobarrier makes a difference skipping it is not safe.
I do not fully understand that sentence, what do you mean by "makes a 
difference" and "skipping is not safe"?

-Georg
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WARNING: multiple messages have this Message-ID (diff)
From: "Georg Schönberger" <g.schoenberger@xortex.com>
To: Christoph Hellwig <hch@infradead.org>,
	Martin Steigerwald <martin@lichtvoll.de>
Cc: Jens Axboe <axboe@kernel.dk>, Jeff Moyer <jmoyer@redhat.com>,
	Linux FS-Devel <linux-fsdevel@vger.kernel.org>,
	Linux Block mailing list <linux-block@vger.kernel.org>,
	XFS mailing list <xfs@oss.sgi.com>
Subject: Re: XFS and nobarrier with SSDs
Date: Mon, 14 Dec 2015 10:18:54 +0000	[thread overview]
Message-ID: <566E978E.2070502@xortex.com> (raw)
In-Reply-To: <20151214095823.GA30662@infradead.org>

On 2015-12-14 10:58, Christoph Hellwig wrote:
> On Mon, Dec 14, 2015 at 09:38:56AM +0100, Martin Steigerwald wrote:
>> Is it safe to use XFS (or any other filesystem) on enterprise SSDs with Power
>> Loss Protection (PLP), i.e. some capacitor to provide for enough electricity
>> to write out all data in DRAM to flash after a power loss, with a reordering
>> I/O scheduler like CFQ?
> If the device does not need cache flushes it should not report requiring
> flushes, in which case nobarrier will be a noop.
OK - that would also mean that mounting with nobarrier should not make a 
performance difference.

> Or to phrase it
> differently:  If nobarrier makes a difference skipping it is not safe.
I do not fully understand that sentence, what do you mean by "makes a 
difference" and "skipping is not safe"?

-Georg

  reply	other threads:[~2015-12-14 10:19 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-12-12 10:24 XFS and nobarrier with SSDs Georg Schönberger
2015-12-12 12:26 ` Martin Steigerwald
2015-12-14  6:43   ` Georg Schönberger
2015-12-14  8:38     ` Martin Steigerwald
2015-12-14  8:38       ` Martin Steigerwald
2015-12-14  9:58       ` Christoph Hellwig
2015-12-14  9:58         ` Christoph Hellwig
2015-12-14 10:18         ` Georg Schönberger [this message]
2015-12-14 10:18           ` Georg Schönberger
2015-12-14 10:27           ` Christoph Hellwig
2015-12-14 10:27             ` Christoph Hellwig
2015-12-14 10:34             ` Georg Schönberger
2015-12-14 10:34               ` Georg Schönberger
2015-12-14 13:36               ` Christoph Hellwig
2015-12-14 16:39               ` Eric Sandeen
2015-12-26 23:44             ` Linda Walsh
2015-12-26 23:44               ` Linda Walsh
2015-12-14 11:48 ` Emmanuel Florac

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