On Mon, Jan 31, 2022 at 04:21:36PM +0100, Kashyap Chamarthy wrote: > On Mon, Jan 31, 2022 at 02:36:46PM +0000, Daniel P. Berrangé wrote: > > On Mon, Jan 31, 2022 at 03:00:33PM +0100, Kashyap Chamarthy wrote: > > > On Mon, Jan 31, 2022 at 12:55:09PM +0000, Daniel P. Berrangé wrote: > > [...] > > > > I briefly wondered if in this "combined" mode whether the no. of > > > duplicate copies can ever fill up the storage. I doubt that, as the > > > combined size of _VARS + _CODE is just about 2MB. So it only starts > > > mattering if you're running tens of thousands of guests. > > > > When guest root / data disk sizes are measured in 100's of MB, or > > GBs, I struggle to get worried about even a 16 MB OVMF blob being > > copied per guest. > > Heh, fair enough. > > > The firmware can be provided in qcow2 format too, so if really > > concerned, just create a qcow2 file with a backing store pointing > > to the readonly master, so you're only paying the price of the > > delta for any guest VARs writes. That's more efficient than what > > we do today with copying the separate raw format VARS.fd file. > > That's nice, I didn't know the qcow2 possibility in this context. For > some reason I assumed the file format always has to be raw here. Your > qcow2 point above should be documented, if it isn't already. Although > I don't know the right place for it. There's already a format field in the descriptor, but even if the firmware is distributed as raw, libvirt can choose to put qcow2 overlay on it, as its all configured with -blockdev Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
