> Op 19 juli 2017 om 10:36 schreef Dan van der Ster <dan@xxxxxxxxxxxxxx>: > > > Hi Wido, > > Quick question about IPv6 clusters which you may have already noticed. > We have an IPv6 cluster and clients use this as the ceph.conf: > > [global] > mon host = cephv6.cern.ch > > cephv6 is an alias to our three mons, which are listening on their v6 > addrs (ms bind ipv6 = true). But those mon hosts are in fact dual > stack -- our network infrastructure does not (yet) allow IPv6-only > hosts. And due to limitations in our DNS service, cephv6.cern.ch is > therefore an alias to 6 addresses -- the three IPv6 + three IPv4 > addresses of the mon hosts. > > Now, when clients connect to this cluster, we have the annoying > behaviour that the Ceph monclient will construct the initial mon hosts > with those 6 addrs, then consult them in random order to find the mon > map. The attempts to the IPv4 addrs fail of course, so the connections > are delayed until they attempt one of the v6 addrs. > > Do you also suffer from this? Did you find a workaround to encourage > the ceph clients to try the IPv6 addrs first? Unfortunately ms bind > ipv6 is not used for clients, and even though getaddrinfo returns IPv6 > addrs first, Ceph randomizes the mon addrs before connecting. > No, sorry, I haven't seen that! When I deploy IPv6 with Ceph it's IPv6-only and those DNS-records will then only contain AAAA-records. Never tried this nor tested it :) Btw, with newer versions you can also use SRV records, might be useful: http://docs.ceph.com/docs/master/rados/configuration/mon-lookup-dns/ Wido > Cheers, Dan _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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