While upgrading OneFS it’s important to keep the InsightIQ software version compatible with the Isilon systems. In this case, InsightIQ wasn’t updated for a while and I had to upgrade from 3.0 -> 3.1 -> 3.2 -> 4.x. The actual upgrade process isn’t too hard (it just takes a lot of time), but there’s one little prerequisite in the 3.1 -> 3.2 upgrade: a minimum free space in the root partition of 502MB. As you can see in the screenshot, I wasn’t even close to the minimum requirement. I got to 357 MB, and that’s after cleaning up redundant stuff. Time to add some more disk space and extend root partition!