[Samba] using vfs module full_audit: longer history?

[Stefan G. Weichinger]

A customer asked "who deleted file X?"  and I noticed that my current
setup only gives me about 4 days of log history ...

Debian uses systemd which runs journald, so I know to use journald.conf
to increase the log file size etc

Any way to specifically increase only the history size for that auditing
module (and not for all the other systemd units)?