No memory reserved for crash kernel.
-
If you run a
systemctl status
as in the truncated output below:List just the failed units. This show that kdump.service has failed.
# systemctl list-units --state=failed UNIT LOAD ACTIVE SUB DESCRIPTION ● kdump.service loaded failed failed Crash recovery kernel arming 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. 1 loaded units listed. Pass --all to see loaded but inactive units, too. To show all installed unit files use 'systemctl list-unit-files'.
Find out more information on kdump.service.
# systemctl status kdump.service ● kdump.service - Crash recovery kernel arming Loaded: loaded (/usr/lib/systemd/system/kdump.service; enabled; vendor preset: enabled) Active: failed (Result: exit-code) since Thu 2017-05-25 06:58:43 BST; 10h ago Process: 1446 ExecStart=/usr/bin/kdumpctl start (code=exited, status=1/FAILURE) Main PID: 1446 (code=exited, status=1/FAILURE) May 25 06:58:36 red-hat-enterprise-linux.shared systemd[1]: Starting Crash recovery kernel arming... May 25 06:58:43 red-hat-enterprise-linux.shared kdumpctl[1446]: No memory reserved for crash kernel. May 25 06:58:43 red-hat-enterprise-linux.shared kdumpctl[1446]: Starting kdump: [FAILED] May 25 06:58:43 red-hat-enterprise-linux.shared systemd[1]: kdump.service: main process exited, code=exited,...URE May 25 06:58:43 red-hat-enterprise-linux.shared systemd[1]: Failed to start Crash recovery kernel arming. May 25 06:58:43 red-hat-enterprise-linux.shared systemd[1]: Unit kdump.service entered failed state. May 25 06:58:43 red-hat-enterprise-linux.shared systemd[1]: kdump.service failed. Hint: Some lines were ellipsized, use -l to show in full.
There is a file /etc/default/grub, which contains grub setting, in the file there is a kernel variable called crashkernel, the error has to do with this setting, auto is default, but depending on how much memory you have auto setting is too big, so setting it to a smaller size makes the error go away, but size this accordingly, 128M may not be best practice, read the following link for further information: https://www.kernel.org/doc/Documentation/kdump/kdump.txt
After setting the value to crashkernel=128 and running grub2-mkconfig, then rebooting, it solved the issue.
Makes a grub configuration file.
# grub2-mkconfig -o /boot/grub2/grub.cfg
Reboot.
# systemctl isolate reboot.target
Another
systemctl status
show, degraded has gone now.I guess it is still easier to type reboot, some backward compatibility has been kept; reboot is a link to systemctl
lrwxrwxrwx. 1 root root 16 May 24 22:04 /sbin/reboot -> ../bin/systemctl
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