From the current host:
Hi, DreamHoster! We recently alerted you to an impending operating system upgrade of your individual VPS instance on the host machine, "iad1-vshost75".
The day of your upgrade has arrived! Within the next few hours we'll be upgrading your VPS and its host machine from Ubuntu Linux version 12.04.5 LTS (also known as Precise Pangolin!) to 14.04.5 LTS (aka Trusty Tahr!).
If you have more than one VPS and aren't sure which one is on this host machine, you can check the Support / Data Centers page in your DreamHost Panel, below (just look for the "VPS" section):
The upgrade will be done in two phases. First, we'll upgrade your host machine, which shouldn't take longer than an hour. Once this is complete, we'll begin sequentially upgrading the VPS guests, which may take up to 25 minutes. Keep in mind, this means there are two separate periods during which your VPS (and websites) will be unavailable.
In most cases, you won't need to do anything to prepare for the upgrade. Just kick back and let us handle the tough stuff!
If you are using Ruby or Python, or run a site that relies heavily on specific server packages, we strongly recommend reading through the page below for known changes that may affect you:
We'll email you again immediately before we begin the upgrade process, and again once we've completed our work.
If you've got any questions about any of this, please don't hesitate to contact our technical support team. They're trained and ready to help with any upgrade-related questions or concerns.
Thanks very much for your patience while we work hard to modernize our fleet of servers and bring you the absolute best performance possible!
-The Happy DreamHost Upgrade Robot, Ubuntu Edition