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

[Bob Chen]

There might be a time window between the NBD server's resize and the
client's `re-read size` request. Is it safe?

What about an active `resize` request from the client? Considering some NBD
servers might have the capability to do instant resizing, not applying to
LVM or host block device, of course...


Regards,
Bob

2017-01-13 0:54 GMT+08:00 Stefan Hajnoczi <address@hidden>:

> On Thu, Jan 12, 2017 at 3:44 PM, Alex Bligh <address@hidden> wrote:
> >> On 12 Jan 2017, at 14:43, Eric Blake <address@hidden> 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
>
>