PAL Verses SCOM 2007

Oct 2, 2010 at 1:11 AM

I have perf data for one of my servers analyzed by PAL shows process queue length of 38 and 80% CPU utilization. SCOM data which is sampled at 15 minute intervals and avaraged does not show same CPU utilization for that time period. What is sample period for PAL and is it an average. I tried to explain perf data counters are real time. New to PAL but love the tool. Trying to get hardware replaced but data does not agree.

Oct 6, 2010 at 6:11 AM

PAL slices up the log into time slices and computers statistics (min, max, avg, trend, etc.) for each time slice. It uses the stats in each time slice for it's threshold analysis. The PAL charts plot *every* data point in the log.

The sample period of a log is the rate at which the samples were collected when capturing the data. PAL is not involved in this part because PAL analyzes counter logs after they have been captured.

Not all counters are collecting "real time" data. Each counter is implemented differently. Some counters will be a what is going on at the moment of collection, while others are continuously calculating a window of time. Check the descriptions of the counters you are concerned with to get your answer.

For example, here are excerpts from a few counters:
• \Processor(*)\% Processor Time: “This counter is the primary indicator of processor activity, and displays the average percentage of busy time observed during the sample interval.”
• \System\Context Switches/sec: “This counter displays the difference between the values observed in the last two samples, divided by the duration of the sample interval”
• \LogicalDisk(*)\Current Disk Queue Length: “This is an instantaneous snapshot, not an average over the time interval.”