We are running Munin 2.0.6 on some 64-bit RH5 servers, and have enabled the diskstats plugin. Sometimes the disk latency reported by munin will be negative, this happens more often when there is a lot of IO on the servers. I've traced this problem to the fact that on the RH kernel we are using, the rd_ticks/wr_ticks in /sys/block/*/stat are 32-bit numbers, so when the ticks wraps, a negative value