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? Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@assyoma.it - info@assyoma.it GPG public key ID: FF5F32A8