I've been trying to wrap my head around crush rules, and I need some
help/advice. I'm thinking of using erasure coding instead of
replication, and trying to understand the possibilities for planning for
failure cases.
For a simplified example, consider a 2 level topology, OSDs live on
hosts, and hosts live in racks. I'd like to set up a rule for a 6+3
erasure code that would put at most 1 of the 9 chunks on a host, and no
more than 3 chunks in a rack (so in case the rack is lost, we still have
a way to recover). Some racks may not have 3 hosts in them, so they
could potentially accept only 1 or 2 chunks then. How can something
like this be implemented as a crush rule? Or, if not exactly this,
something in this spirit? I don't want to say that all chunks need to
live in a separate rack because that is too restrictive (some racks may
be much bigger than others, or there might not even be 9 racks).
Thanks,
Andras
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
