Hi Johan, Even if data is consolidated - you will get the max-values - as your RRD's > are set up to keep these. > But looking on a wider scope - you may get a difference on the sum of the > Max - I think... [image: :-)] > Another example. of single samples. > A: 1 2 3 3 2 1 > B: 3 2 1 1 2 3 > > For each of the above - the sum is always 4 - when adding up A and B > numbers. > But when all the 6 values are consolidated to a single value - and you use > MAX - you will end up having 3 for A - and 3 for B. > The sum of these are 6 - (and not 4). > So if larger buckets are created - and the sum of these are calculated you > will end up with a higher number. >
Thank you, that is an easy to understand explanation that seems to demonstrate what I am experiencing. I couldn't get my head around it until I saw that. Basically, my 1 month graph uses a 2 hour consolidation period and my 1 year graph uses a 1 day consolidation period. It is unlikely that MAX(A) and MAX(B) are going to happen at the same time. Let's assume, on my monthly graph that MAX(A) happens in a different 2 hour bucket to MAX(B), but on my yearly graph, MAX(A) and MAX(B) occur within the same bucket as the buckets are larger - the MAX on the yearly graph will be higher than the MAX on the monthly graph. Does that sound plausible? I think I have just convinced myself of the pit falls of using MAX when combining data sources. For network bandwidth it's normal to look at the 95%-percentile > Thanks, I will have a look into this. Chris
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