There are 58 database hosts connected to the private1-c-codfw and private1-d-codfw vlans on the legacy top-of-rack switches in codfw rows C and D. See the full list on P66916.
Similar to what we recently did for rows A and B (T355544) we need to move the network connection on all of these hosts from the current top-of-rack switch they are connected to (asw-xxxxx) to the newer equipment installed in parallel in each rack to replace them (lsw1-xxxx). One lesson from the experience in rows A and B is that approaching this on a rack-by-rack basis is tricky for the DBAs, as it is effectively a random order in terms of the database setup.
Each host can be moved individually, so for this move it is probably best we tackle the DB hosts as a unit, and come up with a schedule of master switchovers, depools and cable moves that overall is least disruptive.
DC-Ops have pre-cabled the switch side of the new links, so the downtime for each host will likely be only a few seconds (although we should probably be prepared for slightly longer). The links will also be moved one-by-one, so no two hosts will be down at any given time.