Re: [libvirt-users] Create qcow2 v3 volumes via libvirt

Il 01-05-2018 10:56 Daniel P. Berrangé ha scritto: > qcow2 is widely used in production at large scale in general. Just not > with internal snapshots - almost everything uses external snapshots, > aka backing file chains. > > The QEMU community still tends to discourage use of internal snapshots. > There are not even any QMP monitor commands to use them - you are forced > to use the legacy HMP interface to QEMU for mgmt. All of the workaround > providing interesting block storage mgmt is focused on external snapshots > (aka the backing_file option). There are some technical downsides to > internal snapshots IIUC, such as inability to free the space used by the > internal snapshot when it is deleted, loading/saving snapshots blocks > execution of the guest OS, and probably more I've forgotten about. > > The only nice thing about internal snapshots is simplicity of mgmt, and > that is a very nice thing indeed, which is why virt-manager has code > to support that - it was much easier to add that code for external > snapshots. Just a shame about all the downsides :-( So internal snapshots remain something very useful for lab/tests, but are not recommended for regular use in production environment, right?