Raspberry Pi - Ramdisk

/etc/fstab

tmpfs /tmp tmpfs defaults,noatime,nosuid,mode=1777,size=48m 0 0
tmpfs /var/tmp tmpfs defaults,noatime,nosuid,mode=1777,size=8m 0 0
tmpfs /var/mail tmpfs defaults,noatime,nosuid,mode=2775,size=4m 0 0
tmpfs /var/log tmpfs defaults,noatime,nosuid,mode=0755,size=96m 0 0
# tmpfs /var/spool tmpfs defaults,noatime,nosuid,mode=0755,size=4m 0 0   # - user crontabs ...

Check what folders already exists and create them when mounting using /etc/tmpfiles.d/beNiceToYourSDCard.conf otherwise non-default services wont start (like apache2 or powerdns ...)

/etc/tmpfiles.d/beNiceToYourSDCard.conf

#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

# See tmpfiles.d(5) for details

### /tmp ###
d /tmp 1777 - - -

### /var/tmp ###
d /var/tmp 1777 - - -

### /var/mail ###
d /var/mail 2775 root mail -

# q /var 0755 - - -
# L /var/run - - - - ../run
### /var/log ###
d /var/log 0755 - - -
f /var/log/wtmp 0664 root utmp -
f /var/log/btmp 0600 root utmp -
### Below dirs need to be created in /var/log(tmpfs)
d /var/log/apache2 750 root adm -
# d /var/log/mysql 2750 mysql adm -
# d /var/log/redis 750 redis redis -
d /var/log/apt 755 root root -
# d /var/log/ntpstats 755 ntp ntp -
# d /var/log/samba 750 root adm -
# d /var/log/systat 755 root root -
d /var/log/journal 2755 root systemd-journal -
d /var/log/openvpn 0755 - - -
d /var/log/private 0700 - - -
d /var/log/runit 0755 - - -
### Below files need to be created in /var/log(tmpfs)
f /var/log/lastlog 0664 root utmp -
f /var/log/faillog 0644 root utmp -

### /var/spool ###
# d /var/spool 0755 - - -
# d /var/spool/rsyslog 0700 - - -
# d /var/spool/powerdns 0755 - - -
# d /var/spool/postfix 0755 - - -

### /var/cache ###
# d /var/cache 0755 - - -

### /var/lib ###
# d /var/lib 0755 - - -

Check failed units after reboot if any

systemctl list-units --failed
systemctl list-units --state failed