On Fri, Feb 7, 2014 at 2:59 PM, Robert Collins <[email protected]> wrote: > On 7 February 2014 23:02, Taurus Cheung <[email protected]> wrote: >> Hi, >> >> >> >> I am working on deploying images to bare-metal machines using nova >> bare-metal. In existing implementation in nova-baremetal-deploy-helper.py, >> there's only 1 worker to write image to bare-metal machines. If there is a >> number of bare-metal instances to deploy, they need to queue up and wait to >> be served by the single worker. Would the future implementation be improved >> to support multiple workers? > > I think we'd all like to do multiple deploys at once, but there are > significant thrashing risks in just running concurrent dd's - for > instance, datacentre networks are faster than single disks (so > cloud-scale architectures have - paradoxically to most folk :)) more > network bandwidth than persistent IO bandwidth. In fact this patch > (https://review.openstack.org/#/c/71219/) reduces a source of > thrashing (based on testing on our prod hardware) to improve overall > performance.
I agree here, and basically saw that exact behavior when I experimented with adding multiple workers to nova-baremetal-deploy-helper, and saw almost no performance improvement. Starting 2 workers just resulted in each individual deploy basically taking twice as long. > > Longer term with Ironic I can see multicast/bittorrent/that sort of > thing being used to achieve efficient concurrency when deploying many > identical images. -- -- James Slagle -- _______________________________________________ OpenStack-dev mailing list [email protected] http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
