So you’ve set up an Azure Stack HCI Cluster and everything’s running great, but there is this nagging feeling in the back of your mind. It’s a hybrid setup, with some type of flash cache sitting in front of spinning disk, and you start to wonder how hard you’re pushing that cache, and how long it will last. Thankfully with Windows Server 2019, there are many in-built tools and commands to help work out just that!
Overview While spending a lot of time on the Storage Spaces Direct Slack group, one thing that comes up, again and again, is patching of S2D Clusters, and what is the best way to do it. For this blog series, I’m going to break down the patching best practices into 2 separate scenarios: Offline Patching Using Cluster Aware Updating Offline Patching Offline patching is a pretty common scenario when patching S2D Clusters, and in my mind it is used for 2 reasons, catching up on multiple months of patching where there are known issues, and planned patching in a small window with an outage.
Storage Spaces Direct (S2D) is an incredibly powerful technology, and makes up a huge part of the new AzureStack HCI Solution, however performing maintenance on it can catch out new players. One of the biggest causes of failures while performing maintenance on S2D hosts and clusters, is that the hosts haven’t been correctly put into maintenance mode, so I set out to simplify the process with 3 new functions. The 3 activities I’ve targeted with these functions are enabling and disabling maintenance mode on a host correctly, and checking the current state of a host or cluster.
I’d like to start with a shout out to Philip Elder, for he came up with the initial idea and script that I’ve used here. One thing that’s not always obvious when dealing with S2D Clusters is how much of your Storage Pool has been provisioned and how much capacity, if any, is left. To help with this, we came up with be script you’ll see at the bottom of this article.