Configure Linux core-dump program to store cores permanently

Question

I am using RHEL operating system, which has its default program systemd-coredump which handles the cores within the node.

Here I see that document says, if Storage=none then dumps will not be stored permanently on the node. So, I have updated my /etc/systemd/coredump.conf to :

cat /etc/systemd/coredump.conf
Storage=external
MaxUse=20%

So, this should throttle the dumps only if reaches 20%. But I see disk space is around 10% even then old core dumps are removed.

$df -h
Filesystem                Size  Used Avail Use% Mounted on
/dev/vda1                  80G  7.7G   73G  10% /
devtmpfs                  3.8G     0  3.8G   0% /dev
tmpfs                     3.9G     0  3.9G   0% /dev/shm
tmpfs                     3.9G  1.6M  3.9G   1% /run
tmpfs                     3.9G     0  3.9G   0% /sys/fs/cgroup
/dev/mapper/vg02-volumes   60G   33M   60G   1% /var/lib/origin/openshift.local.volumes
/dev/mapper/vg00-docker    60G  330M   60G   1% /var/lib/docker
tmpfs                     783M     0  783M   0% /run/user/1000

My core-dump dir:

$df /var/lib/systemd/coredump/
Filesystem     1K-blocks    Used Available Use% Mounted on
/dev/vda1       83874796 7978616  75896180  10% /

Am I understanding the doc wrong or missing something here.

Answer 1

if you didn't check this alreday, aging of core files are also controlled via systemd-tmpfiles try checking grep core /usr/lib/tmpfiles.d/* and see what is the config

d /var/lib/systemd/coredump 0755 root root 3d

would say delete core files older than 3days, see if this is the cause for removing old files, if storage space has not crossed the configured limit, you can find more about this in linux documentation.