Linux | Systemd units
Systemd is a suite of basic building blocks for a Linux system. It provides a system and service manager that runs as PID 1 and starts the rest of the system.
The Netdata Agent monitors the systemd slice units state. The
systemd_slice_units_state alert indicates that one or more of the systemd slice units are in the failed state. A systemd slice unit “failed” when the service process returned error code on exit, or crashed, an operation timed out, or after too many restarts. The cause of a failed states is stored in a log.
Read more about systemd
Here is some useful information about systemd from wikipedia 1
Systemd includes features like on-demand starting of daemons, snapshot support, process tracking, and Inhibitor Locks. Systemd is not just the name of the
init daemon, but also refers to the entire software bundle around it, which, in addition to the
init daemon, includes the daemons
networkd, and many other low-level components. In January 2013, Poettering described systemd not as one program, but rather a large software suite that includes 69 individual binaries. As an integrated software suite, systemd replaces the startup sequences and runlevels controlled by the traditional
init daemon, along with the shell scripts executed under its control. systemd also integrates many other services that are common on Linux systems by handling user logins, the system console, device hotplugging, scheduled execution (replacing cron), logging, hostnames and locales.
systemd is a daemon that manages other daemons, which, including
systemd itself, are background processes.
systemd is the first daemon to start during booting and the last daemon to terminate during shutdown. The
systemd daemon serves as the root of the user space’s process tree. The first process (
PID1) has a special role on Unix systems, as it replaces the parent of a process when the original parent terminates. Therefore, the first process is particularly well suited for the purpose of monitoring daemons.
Systemd executes elements of its startup sequence in parallel, which is theoretically faster than the traditional startup sequence approach. For inter-process communication (IPC),
systemd makes Unix domain sockets and D-Bus available to the running daemons. The state of systemd itself can also be preserved in a snapshot for future recall.
Systemd’s core components include the following:
systemdis a system and service manager for Linux operating systems.
systemctlis a command to introspect and control the state of the systemd system and service
manager. Not to be confused with sysctl.
systemd-analyzemay be used to determine system boot-up performance statistics and retrieve
other state and tracing information from the system and service manager.
See more on systemd-slice
The following text originates from the systemd.slice man page.2
A unit configuration file whose name ends in “.slice” encodes information about a slice unit. A slice unit is a concept for hierarchically managing resources of a group of processes. This management is performed by creating a node in the Linux Control Group (cgroup) tree. Units that manage processes (primarily scope and service units) may be assigned to a specific slice. For each slice, certain resource limits may be set that apply to all processes of all units contained in that slice. Slices are organized hierarchically in a tree. The name of the slice encodes the location in the tree. The name consists of a dash-separated series of names, which describes the path to the slice from the root slice. The root slice is named -.slice. For example, foo-bar.slice is a slice that is located within foo.slice, which in turn is located in the root slice.slice.
Note that slice units cannot be templated, nor is possible to add multiple names to a slice unit by creating additional symlinks to its unit file.
By default, service and scope units are placed in
system.slice, virtual machines and containers registered with
systemd-machined are found in
machine.slice, and user sessions handled by
The slice specific configuration options are configured in the
[Slice] section. Currently, only generic resource control settings as described in systemd.resource-control(5) are allowed.
When a slice is in a failed state, you should always try to gather more information about it.
Identify which slice units fail. Open the Netdata dashboard, find the current active alarms under the active alarms tab and look into its chart. (
systemdunits_slice_units.slice_unit_state). In this chart, identify which slice units are in state with value 5.
Gather more information about the failing slice unit
root@netdata~ # systemctl status <slice_name>.slice
Check the log messages from the command of step 2.