On Thu, Apr 03, 2014 at 07:08:34PM +0200, Lukáš Czerner wrote: > All that said, while discard is a interesting functionality and can > be abused in many _many_ ways. It looks like what you really need is > something that is currently available in fallocate(1) from > util-linux package. The option to look for is --dig-holes: > > -d, --dig-holes > Detect and dig holes. Makes the file sparse in-place, without using extra disk space. > The minimal size of the hole depends on filesystem I/O block size (usually 4096 bytes). > Also, when using this option, --keep-size is implied. > > You can think of this as doing a "cp --sparse" and renaming the dest file as the origi‐ > nal, without the need for extra disk space. This applies to single host files right? virt-sparsify takes a disk image and sparsifies it, by examining the internals of the disk image to find unused space (not *zero* space, but space that's unused -- it could contain deleted files or other garbage). Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
