On Fri, Nov 11, 2011 at 14:51, Sage Weil <[email protected]> wrote: >> 2. Why are 2 racks are not enough for 2 failure domains? >> From the commit: >> If there are >2 racks, separate across racks. > > Well, technically they are. My worry is that it's more likely that racks > will have significantly vary capacity (i.e. crush weight) due to, say, 1 > full rack and a second 1/2 rack. If the policy forces replicas be placed > across racks things won't balance well. > > I suppose there should be an argument like --min-racks that controls that > threshold?
In theory the operator can shoot themselves in the foot if they so please. It seems like a Ceph management console could warn about "imbalanced crush weight" across racks. This would also allow the cluster operator to check on their balance over time assuming hardware gets replaced over time. This could introduce larger rotational hdds, or smaller ssds, across the cluster. Kelly -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
