Questions about percentile line value changes when resizing the window

[HoodieQ]

I created a custom graph for one of my hosts to monitor the network interface. In that graph, I enabled the percentile line to see my monthly real-time 95th percentile line. Everything has gone well in the first 5 days, after that, I witnessed a significant drop in my 95th percentile line, which was weird. I looked into the graph and found that the graph was displaying less data, the sampling interval has become larger, which led to different results of the 95th percentile calculation. So I enlarge the browser window, and not surprisingly, the graph showed more data and the 95th percentile value became normal.

So the problem is, whether the 95th percentile line is calculating the result using the full dataset is depending on the window size? That doesn't make sense at all, because reducing the sample size will lead to unreliable calculation results, and there is always a limitation of the window size.
How can I get the calculation result with the full dataset(within the selected period)?

Here are the screenshots, notice I have selected the "This month so far" period and the screenshot is part of the graph, the full graph is too long to display here. The two screenshots show a huge difference in results.

The graph in smaller window size


The graph in larger window size

[HoodieQ]

It seems like the calculation is based on the trend data instead of the real history data, is there any solution for that? I really want to get the accurate result of my 95th percentile.

[HoodieQ]

How long do you keep data? If there is no more data, only tends, its not really possible to use that data...

Good point. I did notice that the previous historical data would miss if the maximum storage period is exceeded; instead, the trend data still exist. But the thing is, the results of percentile calculation change as resizing the browser window, as shown in the figure I posted.
As you mentioned, I increased the storage period to 180d while it was 7d before. However, I don't think it will work because the window size still affects the percentile result. The comparison result of my 2 monitors(1080p, 1440p) shows a significant difference in the same period of [now-5d to now].

[ooc_zaza_za]

Hi HoodieQ,

Can you please assist in creating the 95th percentile line, how do you do that? I'm quite new to Zabbix and from the documentation I could not understand.