Have you tested this or just guessing that the libvirt driver in nova isn't doing the right thing? Because multiattach disks are always set to cache mode "none":
https://github.com/openstack/nova/blob/20bc0136d0665bafdcd379f19389a0a5ea7bf310/nova/virt/libvirt/driver.py#L423-L426 # Shareable disks like for a multi-attach volume need to have the # driver cache disabled. if getattr(conf, 'shareable', False): conf.driver_cache = 'none' ** Changed in: nova Status: New => Invalid -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1788619 Title: disk cachemodes should be restricted with multiattached volumes Status in Cinder: New Status in OpenStack Compute (nova): Invalid Bug description: If using multiattach, the "writeback" and "unsafe" disk_cachemode options presumably break the semantics that an application writing to a clustered datastore would rely on for data consistency between multiple nodes. Volumes should not be allowed to attach to multiple instances (multiattach) with unsafe cache modes. (This may even include writethrough? I'm not sure.) To manage notifications about this bug go to: https://bugs.launchpad.net/cinder/+bug/1788619/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
