Re: [libvirt] [PATCH 2/2] Adjust block size used by dd to speed QEMU domain save operations.

On Fri, Jun 04, 2010 at 08:23:32AM -0600, Eric Blake wrote: > In that case, it may be better to have two constants - the preferred > transfer size (1M), and the XML padding block size (512 as before, or > perhaps 4k given newer disk architectures that prefer 4k), along with > code that allows the final transfer to be shorter than the preferred > size so long as it is still a multiple of the block size. > That doesn't work because dd can't seek into the file a size less than its transfer size. ie the seek=NN parameter is specifying a multiple of the bs=XX value, not an absolute seek position in bytes.