Tomorrow (June 11th) at 1600 UTC, we will be failing over the primary NFS server to do maintenance and upgrades on it. The secondary partner in the cluster is already upgraded and ready, and recent changes *should* make it a fairly straightforward failover with a brief period of high load. If it doesn't proceed smoothly, it will be a slightly longer period of high load and NFS lockup as failover completes (10-20 min or so). After maintenance it will be failed back, which will also, hopefully, be quick and painless.

-- 
Brooke Storm
SRE
Wikimedia Cloud Services
bstorm@wikimedia.org
IRC: bstorm_