Why does it show a larger volume of disks?

Question

System administration

To determine the amount of free space on the zabbix platform, I use the expression vfs.fs.size[C:,free], but for some reason on many machines it incorrectly determines the amount of free space. That is, in fact, there are 394 gigs of free space, but it shows on the graph that 426 gigs are free. Of the 7 machines, only two have the correct volume, while the data element is the same everywhere. What could be the problem?

Answer 1

The units of measurement are different. There are metric "gigabytes" and there are IT "giBibytes"
https://ru.wikipedia.org/wiki/Binary_prefixes
425(GB)*(1000*1000*1000)/(1024*1024*1024)~=395(GiB)
Well, a little more rounded clumsily.