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 > > <[email protected]>: > > > > > 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 > _______________________________________________ > Dng mailing list > [email protected] > https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng > -- Please do not email me anything that you are not comfortable also sharing with the NSA. _______________________________________________ Dng mailing list [email protected] https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
