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 <stefa...@gmail.com>: > On Thu, Jan 12, 2017 at 3:44 PM, Alex Bligh <a...@alex.org.uk> wrote: > >> On 12 Jan 2017, at 14:43, Eric Blake <ebl...@redhat.com> 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 > >
