On Fri Jul 22 11, C. P. Ghost wrote: > On Fri, Jul 22, 2011 at 8:44 AM, Unga <unga...@yahoo.com> wrote: > > Hi all > > > > How to sync a file on FreeBSD (esp. on 8.1) to disk? > > > > I used fsync(2), but does not immediately flush to disk. > > > > I want my writing to a file (a log file) immediately available to other > > users to read.
if you *really* want to see data being written to disk immediately and don't care about performance, do the following: 1) disable the write cache of your hdd (see ada(4) and ata(4) man pages) 2) mount your partition(s) with '-o sync' cheers. alex > > It shouldn't matter: as soon as write(2) completes, the > system-wide file cache -- not the disk -- is updated, and > other users will transparently read(2) from that cache, > not from the disk. > > What you probably want is to flush the userspace buffers > of your I/O library as soon as you write a line of output: > See fflush(3), set[v]buf(3)... You may also use a non-buffered > stream for writing logs. > > fsync(2) has other uses. In particular, it is of NO use as > long as the logging application doesn't flush its I/O caches > itself. > > > Best regards > > Unga > > -cpghost. > > -- > Cordula's Web. http://www.cordula.ws/ _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"
