On Jun 16, 2012 8:37 PM, "Xin LI" <delp...@gmail.com> wrote: > > On Sat, Jun 16, 2012 at 12:01 PM, Chris Rees <utis...@gmail.com> wrote: > > On Jun 14, 2012 5:49 AM, "Wojciech Puchar" < woj...@wojtek.tensor.gdynia.pl> > > wrote: > >>>> > >>>> file to take 900MB or... can i call some system function to "punch" > >>>> holes? > >>> > >>> > >>> I think you can only truncate the file at this time, pretty much like > >>> brk() works for memory. > >> > >> > >> > >> BAD. suppose i keep windoze VM image on filesystem which takes 10GB but > > uses 5GB. > >> > >> i could write simple program to find out what blocks are unused and > > then...do nothing. > >> > > > > What if you cp it? > > That would be a dd(1) unless we teach cp(1) how to do sparse. I think > what he wanted is to tell the OS "I don't need block XX - YY anymore" > and the OS creates a sparse hole, which is not available at this time.
Sorry, I must have misread. I take it cp would take a file with holes and only copy the data part? i.e. take a 10G file of which 5G is a hole, you'd end up with a 5G file? Chris _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
