Synnefo » snf-ganeti

      # we set here a smaller block size as, due to transport buffering, more

      # than 64-128k will mostly ignored; we use nocreat to fail if the device

      # is not already there or we pass a wrong path; we use notrunc to no

      # attempt truncate on an LV device; we use oflag=dsync to not buffer too

      # much memory; this means that at best, we flush every 64k, which will

      # not be very fast

      suffix = utils.BuildShellCmd(("| dd of=%s conv=nocreat,notrunc"

                                    " bs=%s oflag=dsync"),

                                    real_disk.dev_path,

                                    str(64 * 1024))