- Disk utilization
(Sectors read/written, number of read/write actions, time spent doing IO)
+ - DNS traffic
+ (query types, response codes, opcodes and traffic)
+
- Harddisk temperatures
(Uhm, yeah, temperature of harddisks that is ;)
(Number of running, sleeping, zombie, ... processes)
- Sensors
- (System temperatured and fan rotation speeds)
+ (lm_sensors voltages, temperatures and fan rotation speeds)
- Serial
(RX and TX of serial interfaces)