Re: [Nbd] [Qemu-block] [Qemu-devel] How to online resize qemu disk with nbd protocol?

[Stefan Hajnoczi <stefanha@...17...>]

On Thu, Jan 12, 2017 at 3:44 PM, Alex Bligh <alex@...872...> wrote:
>> On 12 Jan 2017, at 14:43, Eric Blake <eblake@...696...> wrote:
>> That's because the NBD protocol lacks a resize command.  You'd have to
>> first get that proposed as an NBD extension before qemu could support it.
>
> Actually the NBD protocol lacks a 'make a disk with size X' command,
> let alone a resize command. The size of an NBD disk is (currently)
> entirely in the hands of the server. What I think we'd really need
> would be a 'reread size' command, and have the server capable of
> supporting resizing. That would then work for readonly images too.

That would be fine for QEMU.  Resizing LVM volumes or host block
devices works exactly like this.

Stefan