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

On Thu, Apr 12, 2018 at 5:42 PM Eric Blake <eblake(a)redhat.com&gt; wrote: > On 04/12/2018 05:24 AM, Richard W.M. Jones wrote: > > > I don't think we have nbd-server in RHEL, and in any case wouldn't it > > be better to use qemu-nbd? > > > > You just start a new qemu-nbd process instead of faffing around with > > configuration files, kill the qemu-nbd process when you're done, and > qemu-nbd supports qcow2 already. > That, and qemu-nbd supports extensions such as NBD_CMD_BLOCK_STATUS and > NBD_OPT_STRUCTURED_REPLY that nbd-server has not implemented yet; a qemu > NBD client talking to a qemu-nbd server is thus going to be able to take > advantage of those extensions for better performance that would not be > possible with a qemu NBD client talking to an nbd-server instance (at > least, not without someone implementing the new features there). And > this is no different from the situation where nbdkit as the server lacks > several features; the current rhv-upload patches use a python plugin to > nbdkit, which is implemented as serializing all requests; while using > qemu-nbd as the server would allow parallel requests to be in flight > simultaneously. > Right, qemu-nbd will be better. The manual is not very useful - do we have examples somewhere?

<fs> run <fs> list-filesystems <fs> mount /dev/sda1 / <fs> ll /