[ Date Index ] [ Thread Index ] [ <= Previous by date / thread ] [ Next by date / thread => ]
On Sat, 10 Jul 2010 21:01:32 +0100 Simon Waters <simon@xxxxxxxxxxxxxx> wrote: > Curiosity driven question. > > If I write data to my external hard disk, how can I ensure that a read > to verify that data isn't using a cache? Check the source code of the mount/umount command and the shutdown command - the only sure way is to persuade the device that the rest of the system is about to poweroff, at which point it would be too late for the device to clear the cache, therefore you pretend to tell the device that the next operation (at assembly code level) will be to pull the power and the device has to do everything necessary before the operation returns. We do the same with various systems and chipsets, whatever filesystem and whatever the kernel, persuade the device that it is about to lose power and all devices have to get their cached data out of RAM and onto more permanent storage. How you do that is specific to that kind of device. -- Neil Williams ============= http://www.data-freedom.org/ http://www.linux.codehelp.co.uk/ http://e-mail.is-not-s.ms/
Attachment:
pgpso1VMC5Ho2.pgp
Description: PGP signature
-- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/listfaq