)]}'
{"/COMMIT_MSG":[{"author":{"_account_id":1779,"name":"Daniel Berrange","email":"berrange@redhat.com","username":"berrange"},"change_message_id":"a7ee6f6dab8a66efde1afecfbc4d842590b4704f","unresolved":false,"context_lines":[{"line_number":7,"context_line":"Add the libvirt.ephemeral_image_format config option"},{"line_number":8,"context_line":""},{"line_number":9,"context_line":"This allows new ephemeral images to be optionally created"},{"line_number":10,"context_line":"with type qcow2 rather than raw."},{"line_number":11,"context_line":""},{"line_number":12,"context_line":"Wikimedia Labs has been running with this change hacked"},{"line_number":13,"context_line":"into libvirt for many years.  It appears that there"}],"source_content_type":"text/x-gerrit-commit-message","patch_set":8,"id":"fa6399be_a55c8c26","line":10,"updated":"2016-10-11 13:50:25.000000000","message":"What is the rationale for this ?  The code being changed is not making use of any qcow2 features (eg backing files) so the only effect of using qcow2 over raw would be worse performance (since qemu has todo allocation table lookups for qcow2, and writes to new sectors turn into multiple writes in qcow2).\n\nI would only see a benefit in supporting qcow2 if you\u0027re making use of backing files, in order to avoid having to run mkfs each time, but this patch isn\u0027t doing that.","commit_id":"9f9b3b731e8ea8d0bccf252972a7776849e88542"},{"author":{"_account_id":1779,"name":"Daniel Berrange","email":"berrange@redhat.com","username":"berrange"},"change_message_id":"a7ee6f6dab8a66efde1afecfbc4d842590b4704f","unresolved":false,"context_lines":[{"line_number":12,"context_line":"Wikimedia Labs has been running with this change hacked"},{"line_number":13,"context_line":"into libvirt for many years.  It appears that there"},{"line_number":14,"context_line":"is some interest from other users, as per"},{"line_number":15,"context_line":"http://lists.openstack.org/pipermail/openstack-operators/2015-October/008520.html"},{"line_number":16,"context_line":""},{"line_number":17,"context_line":"Change-Id: Ie9e97dccb96c9ff6b82df2dc698db23056a9cc79"}],"source_content_type":"text/x-gerrit-commit-message","patch_set":8,"id":"fa6399be_25495c60","line":15,"updated":"2016-10-11 13:50:25.000000000","message":"This discussion doesn\u0027t make a whole lot of sense wrt current nova code. The initial thread message there is stating that ephemeral defaults to qcow2 and then asks for ability to use raw for better performance.  Nova in fact always uses raw for ephemeral disks","commit_id":"9f9b3b731e8ea8d0bccf252972a7776849e88542"}],"nova/virt/libvirt/imagebackend.py":[{"author":{"_account_id":14819,"name":"Timofey Durakov","email":"timofei.nd@gmail.com","username":"tdurakov"},"change_message_id":"8c5dc61a8a368360fa0a025ce16cc2f8771b8086","unresolved":false,"context_lines":[{"line_number":53,"context_line":"                    \u0027 use_cow_images flag is used instead of this one.\u0027),"},{"line_number":54,"context_line":"    cfg.StrOpt(\u0027ephemeral_format\u0027,"},{"line_number":55,"context_line":"               default\u003d\u0027default\u0027,"},{"line_number":56,"context_line":"               choices\u003d(\u0027raw\u0027, \u0027qcow2\u0027, \u0027default\u0027),"},{"line_number":57,"context_line":"               help\u003d\u0027File type for ephemeral images.  Type qcow2 may be useful\u0027"},{"line_number":58,"context_line":"                    \u0027 in setups that use a small number of base images and\u0027"},{"line_number":59,"context_line":"                    \u0027 rely on disk space overprovisioning.\u0027),"}],"source_content_type":"text/x-python","patch_set":4,"id":"9a061dce_d9dc8175","line":56,"range":{"start_line":56,"start_character":41,"end_line":56,"end_character":48},"updated":"2016-04-06 13:52:42.000000000","message":"Do we really need \u0027default\u0027 here, as \u0027default\u0027 \u003d\u003d \u0027raw\u0027?","commit_id":"df94ce572e03452599efd92c5fc48f0a8894eabd"},{"author":{"_account_id":12932,"name":"Andrew Bogott","email":"andrewbogott@gmail.com","username":"Andrew"},"change_message_id":"b1f43192d4986b701266dff1d89a452647446f83","unresolved":false,"context_lines":[{"line_number":53,"context_line":"                    \u0027 use_cow_images flag is used instead of this one.\u0027),"},{"line_number":54,"context_line":"    cfg.StrOpt(\u0027ephemeral_format\u0027,"},{"line_number":55,"context_line":"               default\u003d\u0027default\u0027,"},{"line_number":56,"context_line":"               choices\u003d(\u0027raw\u0027, \u0027qcow2\u0027, \u0027default\u0027),"},{"line_number":57,"context_line":"               help\u003d\u0027File type for ephemeral images.  Type qcow2 may be useful\u0027"},{"line_number":58,"context_line":"                    \u0027 in setups that use a small number of base images and\u0027"},{"line_number":59,"context_line":"                    \u0027 rely on disk space overprovisioning.\u0027),"}],"source_content_type":"text/x-python","patch_set":4,"id":"9a061dce_9bd5d41d","line":56,"range":{"start_line":56,"start_character":41,"end_line":56,"end_character":48},"in_reply_to":"9a061dce_d9dc8175","updated":"2016-04-06 15:52:43.000000000","message":"In the current implementation we certainly don\u0027t.  I included that in order to leave room to grow, in case additional formats become useful in the future and one of them is selected as the new, better default.\n\nI\u0027m not married to the idea though.","commit_id":"df94ce572e03452599efd92c5fc48f0a8894eabd"}]}