Hi, joe Thanks for your replay. I want to confirm whether we use “--rescan” for another reason. If only for connecting volume, it should be a bug. I will report it soon.
From: Joe Gordon [mailto:joe.gord...@gmail.com] Sent: Wednesday, August 27, 2014 1:12 AM To: OpenStack Development Mailing List (not for usage questions) Subject: Re: [openstack-dev] [OpenStack][Nova]May be performance issues of connect_volume in Nova On Tue, Aug 26, 2014 at 5:36 AM, Wang Shen <ws1...@gmail.com<mailto:ws1...@gmail.com>> wrote: Hi, All I have done some work to test the performance of LUN scanning, use "iscsiadm" with "--rescan" like what Nova dose. In my test, a host connected with a lot of LUNs , more than 1000 LUNs. Because "--rescan" will cause kernel to scan all of the LUNs connected to the host, it costs several minutes to complete the scanning. According to "connect_volume" at line 284 in nova.virt.libvirt.volume.py<http://nova.virt.libvirt.volume.py>: https://github.com/openstack/nova/blob/master/nova/virt/libvirt/volume.py#L252 Nova uses "iscsiadm" with "--rescan" to detect new volume, but this command will scan all of the LUNs, including all the others which already connected to this host. So if a host has a large number of LUNs connected to it, the connect_volume will be very slow. I think connect_volume needn't scan all of the LUNs, only need scan the LUN specified by connection_info. Is it necessary to discuss a more efficient way to improve this issues. It sounds like this is a bug; we use https://bugs.launchpad.net/nova to track bugs so they don't get lost. -- Best wishes ====================== Peter.W ====================== _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org<mailto:OpenStack-dev@lists.openstack.org> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
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