Considerable size difference between mysql versions We usually employ different MySQL versions for different scenarios. And I realized that similar databases, whith the same amount of tables and data, just because of different mysql versions differs in size from 43M to 223M. (~5x more)

My goal is understand why of that 5x more disk space required..

Some version 5.5.46 have this size:

du -hs /var/lib/mysql/
43M


And some 5.7.11 habe this size:

du -hs /var/lib/mysql/
223M


Inside of it, we use to have those default datafiles like: ib_logfile0, ib_logfile1, ibdata1, mysql..

Within 5.5.46 thay usually have this sizes respectively:

5.1M   ib_logfile0
5.1M   ib_logfile1
26M   ibdata1
6.5M   mysql


..but within 5.7.11 are waaay bigger:

48M   ib_logfile0
48M   ib_logfile1
76M   ibdata1
12M   have also this ibtmp1
25M   mysql


In order to understand all that difference, I took a look to release notes where Oracle writes down what they're changing: https://dev.mysql.com/doc/relnotes/mysql/5.5/en/

But could not find something conclusive.
I appreciate your help on that.
I suggest looking at the 5.6/5.7 release notes to see what changed from 5.5.

ib_logfile file size are because the innodb_log_file_size changed from the outrageously small value of 5M to something that actually performs when people update any modest amount of data.

The ibdata1 increase in size might be a result of utf8_mb4 being the default.

System tables support more features and have some bigger fields.

Overall, its not that much. Are you really running on an embedded processor?