On Friday, Feb 19 we'll be migrating our NFS and production servers onto newer hardware backed by SSDs and more RAM.
This will involve a couple hours of downtime (but hopefully not too many). We'll try to keep it quick.
It will take place in the evening (10pm or later).
Update 2/19: We're pushing this back until Saturday, Feb 20 evening.
Update 2/20 11:50pm: This is done after about 30 minutes in read-only mode and about two minutes minutes of actual downtime. Some VMs will be moving over to jaws now to increase their performance, but the bulk of the work is done and you shouldn't notice any more issues.