Next-generation Mac Performance Tool
Optimize your SSD performance
I can't run the Benchmark...
Unable to find a writable volume on this disk
You need to have write permissions and at least 5 GB of space available on the disk. Select a directory manually or free up at least 5 GB of space and try again.
Sounds like Sensei could not find a writable volume on your drive. Browsing and selecting a volume manually should work.