Can we specify percentage value for RuntimeMaxUse attribute in journald.conf

Question

From man page of Journald.conf I came to know that, by default Journal use 10% of file system size for storing journal files.

I have configured below values in journald.conf.

RuntimeMaxUse=10
#RuntimeKeepFree=
RuntimeMaxFileSize=2G
RuntimeMaxFiles=3

I have not specified any units for

RuntimeMaxUse attribute

How journal treats this value?

one more question below

Is there anyway to specify in journald.conf file to use 30% of the filesystem size for journal files?

For the above configuration, I could see below results on my system

-rw-r-----+ 1 root root 904M Jul 14 14:11 system@63691df841d14d4795850417936c799e-0000000006cdd9d1-0005379686115fe8.journal
-rw-r-----+ 1 root root 904M Jul 14 14:14 system@63691df841d14d4795850417936c799e-0000000006e30c11-00053796905a72d8.journal
-rw-r-----+ 1 root root 120M Jul 14 14:14 system.journal

Two files created with approximately 1G each and third file can grow upto 1G and after that oldest journal files gets deleted.

For one more configuration below,

RuntimeMaxUse=2G
#RuntimeKeepFree=
RuntimeMaxFileSize=2G
RuntimeMaxFiles=3

Even though i specified RuntimeMaxUse as 2G, I could see journal uses 3G of file system size. i.e

1) file1 -- system@*********************** - 1G
2) file2 -- system@*********************** - 1G
3) file3 -- system.journal                 - Reaches upto 1G

Is my understanding correct?

Please clarify.

Answer 1

No, you cannot specify a percentage value for RuntimeMaxUse or any other storage option from journald.conf as Jan Synacek explains here:

The values are not specified in percentages, they are specified in absolute values followed by a unit. The percentages mentioned in the manpage are applied only if the user specifies no value for a given option.

So only absolute values followed by a unit will work.