How to increase dmesg buffer size in CentOs 7.2?

Question

I am getting following message in dmesg:

"systemd-journald[414]: /dev/kmsg buffer overrun, some messages lost."

How to increase dmesg log buffer size to view all debug messages? Any help will be appreciated.

Solution

The easiest way to do this would probably be to append:

log_buf_len=<size>

To your grub line.

in other words, edit /etc/default/grub so that the line:

GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=cl/root rd.lvm.lv=cl/swap"

Becomes:

GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=cl/root rd.lvm.lv=cl/swap log_buf_len=5M"

Change 5M to whatever size you require

Then run:

grub2-mkconfig --output=/boot/grub2/grub.cfg

To regenerate grub.