Overview

This article provides information on what is a Rolling Restart and what it implies for a Jive site and its users.

Environment

Jive Hosted and On-Premise.

Information

From a very high level, a rolling restart takes advantage of the application's clustering architecture to restart the individual servers with minimal interruption to end-users. As opposed to a full restart where the site is unavailable while the servers are starting up, users will be able to use the service during a rolling restart.

Details and impact

From a technical perspective, what we're doing is shutting down each machine individually and relying on the load balancer to redirect traffic away from the downed node. This action has a few noticeable effects on users:

• Users who have not opted for the site to "Remember Me" will need to log in again. This behavior occurs because users' sessions are tied to a particular node, so when they are directed to another node they will need to re-authenticate their session.

• Users who try to access the site may experience a temporary "site down" error before the load balancer begins redirecting traffic.

• Per-node, in-memory state such as auto-saved RTE posts will be lost.

As with any restart, the node will be sluggish at first. This happens while the node's fast memory caches are being populated from disk. The node should be back to full responsiveness within minutes of normal use.

Estimate time for the rolling restart to complete is dependent on how many nodes the instance has and how busy the nodes are.

Possible Uses

For the most part, a rolling restart accomplishes exactly the same goals as a full restart. Each of the nodes will be brought down in turn, which yields a net effect of a full restart for the entire cluster.

However, there are some limitations to what can be done with a rolling restart and what requires a full restart. For example, while many plugins can be installed via a rolling restart, those that need to install their own database schema cannot. Further, because rolling restarts require manual control, they can only be scheduled during normal business hours. A full restart, on the other hand, is fully automated and can be scheduled for any time.