[ceph-users] Setting temporary CRUSH "constraint" for planned cross-datacenter downtime

My server provider usually does infrastructure maintenance and planned downtimes on a per-datacenter-building granularity, and thus I have a Ceph cluster with that set as the "datacenter" failure domain in CRUSH. However, it now has a planned maintenance that affects two buildings simultaneously. How can I tell Ceph to balance data such that DC1 and DC2 specifically should be treated as the same failure domain? (All other datacenters remain independent; ideally with minimal necessary rebalancing.) Thanks!