WLM is responsible for sampling the MSU Utilization for each LPAR every 10 seconds. Every 5 minutes, WLM documents the highest observed MSU utilization sample from the 10 second bucket. This process keeps a track of the past 48 updates sampled for each LPAR. When the 49th observation is recorded, the 1st observation is discarded, and so on. These 48 observations of 5 minutes each represent a total of 5 minutes * 48 = 240 minutes or the past 4 hours rolling average (R4HA). WLM stores the average of these 48 values in the WLM control block RCT.RCTLACS. Every time RMF creates a Type 70 record, the current 4 hour rolling average from RCT.RCTLACS is populated in the SMF70LAC field representing the 4hour rolling average at the time of cut. This way we have the “4 Hour Rolling Average” being recorded as SMF70LAC for every Type70 record.
The below example shows how 4HRA is calculated. In this example the 4HRA at 04:00 is 271 MSUs which is average of all the 48 intervals of 5 minutes each from 00:00-4:00
OBS TIME MSU/Hr 1 00:00 220 2 00:05 259 3 00:10 278 4 00:15 262 5 00:20 312 6 00:25 225 7 00:30 234 8 00:35 289 9 00:40 285 10 00:45 262 11 00:50 283 12 00:55 310 13 01:00 302 14 01:05 289 15 01:10 263 16 01:15 213 17 01:20 241 18 01:25 173 19 01:30 169 20 01:35 233 21 01:40 279 22 01:45 303 23 01:50 328 24 01:55 313 25 02:00 319 26 02:05 319 27 02:10 280 28 02:15 280 29 02:20 307 30 02:25 293 31 02:30 289 32 02:35 301 33 02:40 249 34 02:45 304 35 02:50 273 36 02:55 277 37 03:00 301 38 03:05 249 39 03:10 211 40 03:15 234 41 03:20 241 42 03:25 278 43 03:30 304 44 03:35 273 45 03:40 277 46 03:45 307 47 03:50 229 48 03:55 304 49 04:00 271
