Subject: Re: o_sync in vfat driver
From: Anton Altaparmakov <aia21@cam.ac.uk>
To: Arjan van de Ven <arjan@infradead.org>
Cc: Lennart Sorensen <lsorense@csclub.uwaterloo.ca>, col-pepper@piments.com,
       linux-kernel@vger.kernel.org
In-Reply-To: <1141050437.2992.111.camel@laptopd505.fenrus.org>
References: <op.s5cj47sxj68xd1@mail.piments.com>
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	 <op.s5kzao2jj68xd1@mail.piments.com> <op.s5lq2hllj68xd1@mail.piments.com>
	 <20060227132848.GA27601@csclub.uwaterloo.ca>
	 <1141048228.2992.106.camel@laptopd505.fenrus.org>
	 <1141049176.18855.4.camel@imp.csi.cam.ac.uk>
	 <1141050437.2992.111.camel@laptopd505.fenrus.org>
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Organization: Computing Service, University of Cambridge, UK
Date: Mon, 27 Feb 2006 14:41:44 +0000
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On Mon, 2006-02-27 at 15:27 +0100, Arjan van de Ven wrote:
> On Mon, 2006-02-27 at 14:06 +0000, Anton Altaparmakov wrote:
> > On Mon, 2006-02-27 at 14:50 +0100, Arjan van de Ven wrote:
> > > On Mon, 2006-02-27 at 08:28 -0500, Lennart Sorensen wrote:
> > > > On Sun, Feb 26, 2006 at 11:50:40PM +0100, col-pepper@piments.com wrote:
> > > > > Hi,
> > > > > 
> > > > > OMG what do I have to do to post here? 10th attempt.
> > > > > {part2}
> > > > > 
> > > > > Here is a non-exhaustive list of typical devices types requiring fat vfat
> > > > > support:
> > > > > 
> > > > > fd ide-hd scsi-hd usb-hd cdrom usb-hd usb-handheld (iPod, iRiver etc)
> > > > > usb-flash (usbsticks, cameras, some music devices.)
> > > > > 
> > > > > IIRC the sync mount option for vfat is ignored for file systems >2G, this
> > > > > effectively (and probably intentionally) excludes nearly all hd partitions
> > > > > and iPod type devices.
> > > > 
> > > > I think many people wish it was ignored on smaller devices too given
> > > > what it does to write performance.
> > > 
> > > well. If you don't want it *DO NOT USE IT AT THE MOUNT COMMAND LINE* !!!
> > 
> > That is easy to say when you are using the command line...  Modern
> > distros (as you know I am sure) mount all hot-plug devices like usb
> > keys, usb hard disks, etc automatically at plug-in time and at least
> > some distros use "-o sync"
> 
> that is a bad misdesign of that distro or at least the tool the distro
> uses for this (I don't know which it is so I can say that without
> sounding partial :)
> 
> the tool that decides to use "sync", or at least the author thereof,
> should be aware of what flash is, and that it has a limited lifespan etc
> etc, and that you thus want maximum caching etc.

I agree completely which is why we hack the system to remove the o_sync
on our distro derivative.  (-:

But my point was that your solution of "don't do that then" is not much
use to your average user who sits in front of such distro in graphical
desktop as they are not technical enough to find and hack their hotplug
system to work properly...

Best regards,

        Anton
-- 
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer / IRC: #ntfs on irc.freenode.net
WWW: http://linux-ntfs.sf.net/ & http://www-stu.christs.cam.ac.uk/~aia21/

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