On Sun, Jan 23, 2011 at 10:35:45PM +0100, Emil Langrock wrote: > there is support for ext4 to use the trim ATA command when a block is freed. I > read that there should be an extra command which does that freeing afterwards. > So is it possible to use that information inside the qcow to mark those > sectors as free? This would make it possible to shrink the size of an image > significantly using some offline (maybe also some online) tools. If the qemu block device can write zeroes out to TRIMmed space, a simple cp --sparse=always <file> <file> (on a raw image) can save all that zeroed space; I recall looking into this sort of thing a while ago and it was fairly simple to write a tool to wipe out the zero blocks in a qcow2 file, too. - Matt -- "The user-friendly computer is a red herring. The user-friendliness of a book just makes it easier to turn pages. There's nothing user-friendly about learning to read." -- Alan Kay -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
