Re: [Libguestfs] [Qemu-block] v2v: -o rhv-upload: Long time spent zeroing the disk

Didn't Rich already try to do that? +def emulate_zero(h, count, offset): + # qemu-img convert starts by trying to zero/trim the whole device. + # Since we've just created a new disk it's safe to ignore these + # requests as long as they are smaller than the highest write seen. + # After that we must emulate them with writes. + if offset+count < h['highestwrite']: Or is the problem that emulate_zero() is only being called if: + # Unlike the trim and flush calls, there is no 'can_zero' method + # so nbdkit could call this even if the server doesn't support + # zeroing. If this is the case we must emulate. + if not h['can_zero']: + emulate_zero(h, count, offset) + return rather than doing the 'highestwrite' check unconditionally even when oVirt supports zero requests?