In LMDB the maximum number of pages is less than the sum of free and used pages?

Hello,

I want to monitor the MDB storage for being too full, and enlarge it manually if necessary.

https://ltb-project.org/documentation/nagios-plugins/check_lmdb_usage can do such monitoring. It calls mdb_stat -fe , parses the lines

Max pages: 2560 Number of pages used: 2559 Free pages: 54

extracts the numbers and calculates either the percent ($pages_used / $max_pages * 100) or ($pages_free / $max_pages * 100 )

As can be seen in this expamle, the maximum number of pages is less than the sum of free and used pages.

Shall the database be enlarged, when ($pages_used / $max_pages * 100) gets too high, or when ($pages_free / $max_pages * 100 ) gets too low?

Greetings Дилян