Planning for systemd

IBM Spectrum Scale™ supports systemd version 219 and later on Linux operating systems.

IBM Spectrum Scale automatically installs and configures itself as a systemd service in systems that have systemd version 219 or later installed. The service unit files are installed in the systemd lib directory, as shown in the following list:

Red Hat Enterprise Linux and SUSE Linux Enterprise Server:
```
/usr/lib/systemd/systemd
```
Ubuntu:
```
/lib/systemd/systemd
```

IBM Spectrum Scale includes the following systemd services. For references to IBM Spectrum Scale daemons, see the descriptions that immediately follow this list:

gpfs: Starts or stops the GPFS™ daemon (mmfsd).
mmccrmonitor: Starts or stops the mmccrmonitor daemon. This service is enabled to start at boot time. It runs all the time. If it is killed by some means other than the systemd systemctl command, restart it manually with the systemctl command.
mmautoload: Starts the mmautoload daemon after the node is rebooted and also starts the GPFS daemon if autostart is specified. This service also shuts down the GPFS daemon when the operating system shuts down.
The systemd manager invokes this service when the node is shut down or rebooted. This service is enabled to start at boot time after mmccrmonitor is started. It cannot be started or stopped with the systemd systemctl command.
mmsdrserv: Starts or stops the mmsdrserv daemon. This service is started after the node is rebooted and is stopped after the GPFS daemon is started. It is also stopped as needed by other GPFS systemd services.
mmsysmon: Starts or stops system health monitoring in a cluster in which the Clustered Configuration Repository (CCR) is enabled. This service is enabled to start when the node is booted and is meant to run continuously until the node is shut down. It also can be started by other services.
lxtrace: Does trace operations. This service is controlled by the mmtracectl command. Do not start or stop this service with the systemctl command.

Descriptions of the IBM Spectrum Scale daemons:

The GPFS daemon (mmfsd) is the main IBM Spectrum Scale daemon that runs on the node.
The mmccrmonitor daemon starts and stops the mmsdrserv daemon if mmfsd is not running.
The mmsdrserv daemon provides access to configuration data to the rest of the nodes in the cluster when the mmfsd daemon is not running.
The mmautoload daemon sets up GPFS resources when the operating system is started.