Saturday, August 10, 2019

How rolling four hour average is calculated

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

OBSTIMEMSU/Hr
100:00220
200:05259
300:10278
400:15262
500:20312
600:25225
700:30234
800:35289
900:40285
1000:45262
1100:50283
1200:55310
1301:00302
1401:05289
1501:10263
1601:15213
1701:20241
1801:25173
1901:30169
2001:35233
2101:40279
2201:45303
2301:50328
2401:55313
2502:00319
2602:05319
2702:10280
2802:15280
2902:20307
3002:25293
3102:30289
3202:35301
3302:40249
3402:45304
3502:50273
3602:55277
3703:00301
3803:05249
3903:10211
4003:15234
4103:20241
4203:25278
4303:30304
4403:35273
4503:40277
4603:45307
4703:50229
4803:55304
4904:00271