現状の初号機と弐号機はCentOS7.6 のminimal でインストールしたものをベースに少しずつインストールをしていっているが、現時点でどれだけサービス/デーモンが上がっているか確認。
個別に見ていって、不要そうなものを切っていく。現状では、下記の43個が上がっている。minimalでインストールしたこともあってか、以前にCentOS 7.2でサーバー立てようとしたときと比べると、若干減っている。
$ systemctl list-units --type=service UNIT LOAD ACTIVE SUB DESCRIPTION auditd.service loaded active running Security Auditing Service chronyd.service loaded active running NTP client/server crond.service loaded active running Command Scheduler dbus.service loaded active running D-Bus System Message Bus firewalld.service loaded active running firewalld - dynamic firewall daemon getty@tty1.service loaded active running Getty on tty1 irqbalance.service loaded active running irqbalance daemon kmod-static-nodes.service loaded active exited Create list of required static device nodes for the current kernel lvm2-lvmetad.service loaded active running LVM2 metadata daemon lvm2-monitor.service loaded active exited Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling lvm2-pvscan@8:18.service loaded active exited LVM2 PV scan on device 8:18 lvm2-pvscan@8:33.service loaded active exited LVM2 PV scan on device 8:33 lvm2-pvscan@8:49.service loaded active exited LVM2 PV scan on device 8:49 lvm2-pvscan@8:65.service loaded active exited LVM2 PV scan on device 8:65 network.service loaded active exited LSB: Bring up/down networking NetworkManager-wait-online.service loaded active exited Network Manager Wait Online NetworkManager.service loaded active running Network Manager polkit.service loaded active running Authorization Manager postfix.service loaded active running Postfix Mail Transport Agent rhel-dmesg.service loaded active exited Dump dmesg to /var/log/dmesg rhel-domainname.service loaded active exited Read and set NIS domainname from /etc/sysconfig/network rhel-import-state.service loaded active exited Import network configuration from initramfs rhel-readonly.service loaded active exited Configure read-only root support rsyslog.service loaded active running System Logging Service smartd.service loaded active running Self Monitoring and Reporting Technology (SMART) Daemon sshd.service loaded active running OpenSSH server daemon systemd-journal-flush.service loaded active exited Flush Journal to Persistent Storage systemd-journald.service loaded active running Journal Service systemd-logind.service loaded active running Login Service systemd-random-seed.service loaded active exited Load/Save Random Seed systemd-readahead-collect.service loaded active exited Collect Read-Ahead Data systemd-readahead-replay.service loaded active exited Replay Read-Ahead Data systemd-remount-fs.service loaded active exited Remount Root and Kernel File Systems systemd-sysctl.service loaded active exited Apply Kernel Variables systemd-tmpfiles-setup-dev.service loaded active exited Create Static Device Nodes in /dev systemd-tmpfiles-setup.service loaded active exited Create Volatile Files and Directories systemd-udev-trigger.service loaded active exited udev Coldplug all Devices systemd-udevd.service loaded active running udev Kernel Device Manager systemd-update-utmp.service loaded active exited Update UTMP about System Boot/Shutdown systemd-user-sessions.service loaded active exited Permit User Sessions systemd-vconsole-setup.service loaded active exited Setup Virtual Console tuned.service loaded active running Dynamic System Tuning Daemon yum-cron.service loaded active exited Run automatic yum updates as a cron job LOAD = Reflects whether the unit definition was properly loaded. ACTIVE = The high-level unit activation state, i.e. generalization of SUB. SUB = The low-level unit activation state, values depend on unit type. 43 loaded units listed. Pass --all to see loaded but inactive units, too. To show all installed unit files use 'systemctl list-unit-files'.
いくつか、「SUB」の欄が”exited”になっているものもあるが、これは別に以上でもなんでもないらしい。
無効になってるサービスも調べてみようということで、systemctl のオプションを変えて試してみた。
$ systemctl list-unit-files -t service UNIT FILE STATE arp-ethers.service disabled auditd.service enabled autovt@.service enabled blk-availability.service disabled brandbot.service static chrony-dnssrv@.service static chrony-wait.service disabled chronyd.service enabled console-getty.service disabled console-shell.service disabled container-getty@.service static cpupower.service disabled crond.service enabled dbus-org.fedoraproject.FirewallD1.service enabled dbus-org.freedesktop.hostname1.service static dbus-org.freedesktop.import1.service static dbus-org.freedesktop.locale1.service static dbus-org.freedesktop.login1.service static dbus-org.freedesktop.machine1.service static dbus-org.freedesktop.NetworkManager.service enabled dbus-org.freedesktop.nm-dispatcher.service enabled dbus-org.freedesktop.timedate1.service static dbus.service static debug-shell.service disabled dm-event.service static dracut-cmdline.service static dracut-initqueue.service static dracut-mount.service static dracut-pre-mount.service static dracut-pre-pivot.service static dracut-pre-trigger.service static dracut-pre-udev.service static dracut-shutdown.service static ebtables.service disabled emergency.service static firewalld.service enabled fstrim.service static getty@.service enabled halt-local.service static initrd-cleanup.service static initrd-parse-etc.service static initrd-switch-root.service static initrd-udevadm-cleanup-db.service static iprdump.service disabled iprinit.service disabled iprupdate.service disabled irqbalance.service enabled kdump.service disabled kmod-static-nodes.service static lvm2-lvmetad.service static lvm2-lvmpolld.service static lvm2-monitor.service enabled lvm2-pvscan@.service static mdadm-grow-continue@.service static # 初号機のみ mdadm-last-resort@.service static # 初号機のみ mdmon@.service static # 初号機のみ mdmonitor.service enabled # 初号機のみ messagebus.service static microcode.service enabled NetworkManager-dispatcher.service enabled NetworkManager-wait-online.service enabled NetworkManager.service enabled plymouth-halt.service disabled plymouth-kexec.service disabled plymouth-poweroff.service disabled plymouth-quit-wait.service disabled plymouth-quit.service disabled plymouth-read-write.service disabled plymouth-reboot.service disabled plymouth-start.service disabled plymouth-switch-root.service static polkit.service static postfix.service enabled quotaon.service static rc-local.service static rdisc.service disabled rescue.service static rhel-autorelabel-mark.service disabled rhel-autorelabel.service enabled rhel-configure.service enabled rhel-dmesg.service enabled rhel-domainname.service enabled rhel-import-state.service enabled rhel-loadmodules.service enabled rhel-readonly.service enabled rsyslog.service enabled selinux-policy-migrate-local-changes@.service static serial-getty@.service disabled smartd.service enabled sshd-keygen.service static sshd.service enabled sshd@.service static systemd-ask-password-console.service static systemd-ask-password-plymouth.service static systemd-ask-password-wall.service static systemd-backlight@.service static systemd-binfmt.service static systemd-bootchart.service disabled systemd-firstboot.service static systemd-fsck-root.service static systemd-fsck@.service static systemd-halt.service static systemd-hibernate-resume@.service static systemd-hibernate.service static systemd-hostnamed.service static systemd-hwdb-update.service static systemd-hybrid-sleep.service static systemd-importd.service static systemd-initctl.service static systemd-journal-catalog-update.service static systemd-journal-flush.service static systemd-journald.service static systemd-kexec.service static systemd-localed.service static systemd-logind.service static systemd-machine-id-commit.service static systemd-machined.service static systemd-modules-load.service static systemd-nspawn@.service disabled systemd-poweroff.service static systemd-quotacheck.service static systemd-random-seed.service static systemd-readahead-collect.service enabled systemd-readahead-done.service indirect systemd-readahead-drop.service enabled systemd-readahead-replay.service enabled systemd-reboot.service static systemd-remount-fs.service static systemd-rfkill@.service static systemd-shutdownd.service static systemd-suspend.service static systemd-sysctl.service static systemd-timedated.service static systemd-tmpfiles-clean.service static systemd-tmpfiles-setup-dev.service static systemd-tmpfiles-setup.service static systemd-udev-settle.service static systemd-udev-trigger.service static systemd-udevd.service static systemd-update-done.service static systemd-update-utmp-runlevel.service static systemd-update-utmp.service static systemd-user-sessions.service static systemd-vconsole-setup.service static teamd@.service static tuned.service enabled wpa_supplicant.service disabled yum-cron.service enabled 148 unit files listed.
今度は大量に出てきた。enabledが自動起動になっているもの、disabledが自動起動が無効になっているもの、staticは単独では自動起動できないものだそうだ。
参考：https://www.server-memo.net/centos-settings/centos7/systemctl-enable.html
あと、これらサービスの起動順序や依存関係も見れるらしい。
参考：https://www.clear-code.com/blog/2015/12/28.html
こんな感じでコマンド打てば、サービスの一覧取得して、そいつを流し込んで、依存関係をテキストに落とす、なんてことも出来る。
$ for name in `systemctl list-unit-files -t service | awk -F'[. ]' '{print $1}'`; do systemctl list-dependencies $name >> service_list.txt ; done
サービスごとの詳細、検討結果は別記事にて。