With all metadata on SSD, and used space filewalker enabled on startup, on restart node will run full speed, reading at 5-10kIOPS peak, exponentially decreasing to normal, as metadata is getting cached, and using about 80-100% of a cpu, for about 10 min. This is the only time I saw storagenode exceed 5% cpu utilization.
Here is my old comment about it Massive reads on startup - #30 by arrogantrabbit, from a different server