On Mon, 9 Jun 2008, Jonathan Hogg wrote: >> Are you sure gdd doesn't create a sparse file? > > One would presumably expect it to be instantaneous if it was creating > a sparse file. It's not a compressed filesystem though is it? /dev/ > zero tends to be fairly compressible ;-)
/dev/zero does not have infinite performance. Dd will perform at least one extra data copy in memory. Since zfs computes checksums it needs to inspect all of the bytes in what is written. As a result, zfs will easily know if the block is all zeros and even if the data is all zeros, time will be consumed. On my system, Solaris dd does not seem to create a sparse file. I don't have GNU dd installed to test with. Bob ====================================== Bob Friesenhahn [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
