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.


--
..med vennlig hilsen = with Kind Regards from Arnt Karlsen
...with a number of polar bear hunters in his ancestry...
Scenarios always come in sets of three:
best case, worst case, and just in case.