Hi Mike, Am 22.07.19 um 17:01 schrieb Mike Christie: > On 07/19/2019 02:42 AM, Marc Schöchlin wrote: >> We have ~500 heavy load rbd-nbd devices in our xen cluster (rbd-nbd 12.2.5, kernel 4.4.0+10, centos clone) and ~20 high load krbd devices (kernel 4.15.0-45, ubuntu 16.04) - we never experienced problems like this. > For this setup, do you have 257 or more rbd-nbd devices running on a > single system? No, these rbd-nbds are distributed over more than a dozen of xen dom-0 systems on our xenservers. > If so then you are hitting another bug where newer kernels only support > 256 devices. It looks like a regression was added when mq and netlink > support was added upstream. You can create more then 256 devices, but > some devices will not be able to execute any IO. Commands sent to the > rbd-nbd device are going to always timeout and you will see the errors > in your log. > > I am testing some patches for that right now. >From my point of view there is no limitation besides io from ceph cluster perspective. Regards Marc _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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