:: Re: [DNG] I've got the automounter …
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Autor: Dr. Nikolaus Klepp
Data:  
Para: dng
Assunto: Re: [DNG] I've got the automounter running
Am Montag, 28. Dezember 2015 schrieb Hendrik Boom:
> On Mon, Dec 28, 2015 at 08:54:29PM +0100, Arnt Karlsen wrote:
> > On Mon, 28 Dec 2015 19:37:08 +0100, Didier wrote in message
> > <56818154.2070004@???>:
> >
> > > Le 28/12/2015 19:22, Simon Hobson a écrit :
> > > > The cache gets written out when the background system processes
> > > > clean up and write the dirty pages out to disk. How long this takes
> > > > depends on tuneable kernel parameters and how busy the system is.
> > > > If the system, and in particular the storage, is otherwise idle
> > > > then IIRC your small file will get written almost instantly. If the
> > > > system is really busy, with a large dirty cache, then it'll take a
> > > > lot longer.
> > >
> > >      That's the logic one would naively expect but I'm not sure of
> > > it. I'm afraid the data remains in the cache and  not backed-up to
> > > disk until some process needs room in the cache. You can do the
> > > experiment of writing data to a usb memory stick and then wait long
> > > after the light has stopped blinking. Then you can either sync or
> > > umount the device and it will blink again for  some time before the
> > > command returns.

> > >
> >
> > ..probably the best way is keep those flashy blinky lights blinking
> > merrily away to try scare the idiots from yanking the removables,
> > while we try finish _all_ the writing to try prepare the media for
> > the inevitable yank, and only then stop the blinky lights and show
> > the "Finished writing to disk, you may now safely remove the disk.
> > Ok." etc eye candy.
>
> (1)
>
> On the Commodore Amiga, users were warned not to remove the floppy disks
> while the disk light was on.
>
> That seemed to work. But the disks were written almost immediately, and
> the OS made sure the disk light stayed on ontil the disk cache was
> cleared.
>
> (2)
>
> Isn't there some kind of mount option saying that buffers should be
> flushed immediately when written to?


In ancient times, when USB flash drives just hit the market, SuSE used the "sync" option when mounting USB devices. It worked - and still does - but decreases performance.

Nik


>
> -- hendrik
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