Remove Old Unused Kernels in Unix
In this article, we are going to demonstrate How to Remove Old Unused Kernels in Unix. The kernel is part of an operating system that stores in a small partition of OS called /boot. Whenever we update/upgrade a system, it will install all required updates along with the kernel images but on the same side, it will not remove old unused kernels after update/upgrade.
It is required to clean old unused kernels to release space from /boot to avoid out of space. And also if it becomes out of space partition /boot then neither we can upgrade the system nor install available kernels. Let’s start removing old unused old kernels.
List out all installed kernels in the system.
[root@DBsGuruN3 ~]# rpm -qa | grep kernel
kernel-uek-5.4.17-2102.204.4.2.el8uek.x86_64
kernel-uek-devel-5.4.17-2011.7.4.el8uek.x86_64
kernel-uek-5.4.17-2011.7.4.el8uek.x86_64
kernel-tools-4.18.0-240.el8.x86_64
kernel-tools-libs-4.18.0-240.el8.x86_64
abrt-addon-kerneloops-2.10.9-20.0.1.el8.x86_64
kernel-headers-4.18.0-240.el8.x86_64
kernel-devel-4.18.0-240.el8.x86_64
[root@DBsGuruN3 ~]#
[root@DBsGuruN3 ~]# yum list kernel-uek
Last metadata expiration check: 0:41:50 ago on Mon 16 Aug 2021 05:53:24 PM IST.
Installed Packages
kernel-uek.x86_64 5.4.17-2011.7.4.el8uek @anaconda
kernel-uek.x86_64 5.4.17-2102.204.4.2.el8uek @ol8_UEKR6
Available Packages
kernel-uek.src 5.4.17-2102.204.4.2.el8uek ol8_UEKR6
[root@DBsGuruN3 ~]#
Validate the currently used kernel in the system.
[root@DBsGuruN3 ~]# uname -r
5.4.17-2011.7.4.el8uek.x86_64
or
[root@DBsGuruN3 ~]# uname -a
Linux DBsGuruN3.labdomain 5.4.17-2011.7.4.el8uek.x86_64 #2 SMP Fri Oct 2 14:39:04 PDT 2020 x86_64 x86_64 x86_64 GNU/Linux
Remove old unused kernels: We have available options to remove unused kernels manually as well as automatically.
Manually deletion: In this option, we can pass old unused kernels as many you want.
[root@DBsGuruN3 ~]# dnf remove kernel-headers-4.18.0-240.el8.x86_64 kernel-devel-4.18.0-240.el8.x86_64
Dependencies resolved.
==============================================================================================================================================================================================================
Package Architecture Version Repository Size
==============================================================================================================================================================================================================
Removing:
kernel-devel x86_64 4.18.0-240.el8 @anaconda 47 M
kernel-headers x86_64 4.18.0-240.el8 @anaconda 4.8 M
Removing dependent packages:
annobin x86_64 9.23-1.el8 @AppStream 132 k
gcc-c++ x86_64 8.3.1-5.1.0.2.el8 @ol8_appstream 31 M
gcc-gdb-plugin x86_64 8.3.1-5.1.0.2.el8 @ol8_appstream 334 k
kernel-uek-devel x86_64 5.4.17-2011.7.4.el8uek @ol8_UEKR6 74 M
libtool x86_64 2.4.6-25.el8 @AppStream 2.6 M
mcelog x86_64 3:166-0.0.1.el8 @anaconda 191 k
pcp-pmda-bcc x86_64 5.1.1-3.0.1.el8 @AppStream 282 k
pcp-pmda-bpftrace x86_64 5.1.1-3.0.1.el8 @AppStream 62 k
systemtap x86_64 4.3-4.0.1.el8 @AppStream 0
Removing unused dependencies:
bcc x86_64 0.14.0-4.el8 @AppStream 41 M
bcc-tools x86_64 0.14.0-4.el8 @AppStream 1.7 M
binutils-devel x86_64 2.30-79.0.1.el8 @ol8_appstream 6.4 M
bpftrace x86_64 0.10.0-4.el8 @AppStream 1.6 M
clang x86_64 10.0.1-1.0.1.module+el8.3.0+7827+89335dbf @AppStream 177 k
clang-devel x86_64 10.0.1-1.0.1.module+el8.3.0+7827+89335dbf @AppStream 13 M
clang-libs x86_64 10.0.1-1.0.1.module+el8.3.0+7827+89335dbf @AppStream 96 M
clang-tools-extra x86_64 10.0.1-1.0.1.module+el8.3.0+7827+89335dbf @AppStream 47 M
cmake-filesystem x86_64 3.11.4-7.el8 @AppStream 0
compiler-rt x86_64 10.0.1-1.module+el8.3.0+7827+89335dbf @AppStream 31 M
cpp x86_64 8.3.1-5.1.0.2.el8 @ol8_appstream 28 M
gcc x86_64 8.3.1-5.1.0.2.el8 @ol8_appstream 59 M
glibc-devel x86_64 2.28-127.0.1.el8 @anaconda 1.2 M
glibc-headers x86_64 2.28-127.0.1.el8 @anaconda 1.9 M
isl x86_64 0.16.1-6.el8 @AppStream 3.1 M
libomp x86_64 10.0.1-1.module+el8.3.0+7827+89335dbf @AppStream 965 k
libomp-devel x86_64 10.0.1-1.module+el8.3.0+7827+89335dbf @AppStream 89 k
libstdc++-devel x86_64 8.3.1-5.1.0.2.el8 @ol8_appstream 11 M
libxcrypt-devel x86_64 4.1.1-4.el8 @anaconda 24 k
mokutil x86_64 1:0.3.0-10.el8 @anaconda 87 k
python3-bcc x86_64 0.14.0-4.el8 @AppStream 309 k
python3-netaddr noarch 0.7.19-8.el8 @AppStream 8.4 M
systemtap-client x86_64 4.3-4.0.1.el8 @AppStream 11 M
systemtap-devel x86_64 4.3-4.0.1.el8 @AppStream 8.5 M
zlib-devel x86_64 1.2.11-16.el8_2 @ol8_baseos_latest 138 k
Transaction Summary
==============================================================================================================================================================================================================
Remove 36 Packages
Freed space: 532 M
Is this ok [y/N]: yes
Running transaction check
Transaction check succeeded.
Running transaction test
Transaction test succeeded.
Running transaction
Preparing : 1/1
Running scriptlet: systemtap-4.3-4.0.1.el8.x86_64 1/1
Running scriptlet: systemtap-4.3-4.0.1.el8.x86_64 1/36
Erasing : systemtap-4.3-4.0.1.el8.x86_64 1/36
Erasing : kernel-uek-devel-5.4.17-2011.7.4.el8uek.x86_64 2/36
Erasing : binutils-devel-2.30-79.0.1.el8.x86_64 3/36
Running scriptlet: pcp-pmda-bpftrace-5.1.1-3.0.1.el8.x86_64 4/36
Erasing : pcp-pmda-bpftrace-5.1.1-3.0.1.el8.x86_64 4/36
Running scriptlet: pcp-pmda-bcc-5.1.1-3.0.1.el8.x86_64 5/36
Erasing : pcp-pmda-bcc-5.1.1-3.0.1.el8.x86_64 5/36
Running scriptlet: libtool-2.4.6-25.el8.x86_64 6/36
Erasing : libtool-2.4.6-25.el8.x86_64 6/36
Erasing : bpftrace-0.10.0-4.el8.x86_64 7/36
Erasing : python3-bcc-0.14.0-4.el8.x86_64 8/36
Erasing : bcc-0.14.0-4.el8.x86_64 9/36
Erasing : bcc-tools-0.14.0-4.el8.x86_64 10/36
Erasing : clang-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 11/36
Erasing : clang-tools-extra-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 12/36
Erasing : clang-devel-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 13/36
Erasing : clang-libs-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 14/36
Erasing : libomp-devel-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 15/36
Erasing : gcc-c++-8.3.1-5.1.0.2.el8.x86_64 16/36
Erasing : systemtap-devel-4.3-4.0.1.el8.x86_64 17/36
Erasing : systemtap-client-4.3-4.0.1.el8.x86_64 18/36
Running scriptlet: mcelog-3:166-0.0.1.el8.x86_64 19/36
Erasing : mcelog-3:166-0.0.1.el8.x86_64 19/36
Running scriptlet: mcelog-3:166-0.0.1.el8.x86_64 19/36
Erasing : gcc-gdb-plugin-8.3.1-5.1.0.2.el8.x86_64 20/36
Running scriptlet: gcc-gdb-plugin-8.3.1-5.1.0.2.el8.x86_64 20/36
Erasing : annobin-9.23-1.el8.x86_64 21/36
Erasing : kernel-devel-4.18.0-240.el8.x86_64 22/36
Erasing : libstdc++-devel-8.3.1-5.1.0.2.el8.x86_64 23/36
Erasing : cmake-filesystem-3.11.4-7.el8.x86_64 24/36
Erasing : python3-netaddr-0.7.19-8.el8.noarch 25/36
Erasing : zlib-devel-1.2.11-16.el8_2.x86_64 26/36
Running scriptlet: gcc-8.3.1-5.1.0.2.el8.x86_64 27/36
Erasing : gcc-8.3.1-5.1.0.2.el8.x86_64 27/36
Running scriptlet: glibc-devel-2.28-127.0.1.el8.x86_64 28/36
Erasing : glibc-devel-2.28-127.0.1.el8.x86_64 28/36
Erasing : libxcrypt-devel-4.1.1-4.el8.x86_64 29/36
Erasing : glibc-headers-2.28-127.0.1.el8.x86_64 30/36
Erasing : kernel-headers-4.18.0-240.el8.x86_64 31/36
Running scriptlet: cpp-8.3.1-5.1.0.2.el8.x86_64 32/36
Erasing : cpp-8.3.1-5.1.0.2.el8.x86_64 32/36
Erasing : isl-0.16.1-6.el8.x86_64 33/36
Running scriptlet: isl-0.16.1-6.el8.x86_64 33/36
Erasing : mokutil-1:0.3.0-10.el8.x86_64 34/36
Erasing : compiler-rt-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 35/36
Erasing : libomp-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 36/36
Running scriptlet: libomp-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 36/36
Verifying : annobin-9.23-1.el8.x86_64 1/36
Verifying : bcc-0.14.0-4.el8.x86_64 2/36
Verifying : bcc-tools-0.14.0-4.el8.x86_64 3/36
Verifying : binutils-devel-2.30-79.0.1.el8.x86_64 4/36
Verifying : bpftrace-0.10.0-4.el8.x86_64 5/36
Verifying : clang-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 6/36
Verifying : clang-devel-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 7/36
Verifying : clang-libs-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 8/36
Verifying : clang-tools-extra-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 9/36
Verifying : cmake-filesystem-3.11.4-7.el8.x86_64 10/36
Verifying : compiler-rt-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 11/36
Verifying : cpp-8.3.1-5.1.0.2.el8.x86_64 12/36
Verifying : gcc-8.3.1-5.1.0.2.el8.x86_64 13/36
Verifying : gcc-c++-8.3.1-5.1.0.2.el8.x86_64 14/36
Verifying : gcc-gdb-plugin-8.3.1-5.1.0.2.el8.x86_64 15/36
Verifying : glibc-devel-2.28-127.0.1.el8.x86_64 16/36
Verifying : glibc-headers-2.28-127.0.1.el8.x86_64 17/36
Verifying : isl-0.16.1-6.el8.x86_64 18/36
Verifying : kernel-devel-4.18.0-240.el8.x86_64 19/36
Verifying : kernel-headers-4.18.0-240.el8.x86_64 20/36
Verifying : kernel-uek-devel-5.4.17-2011.7.4.el8uek.x86_64 21/36
Verifying : libomp-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 22/36
Verifying : libomp-devel-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 23/36
Verifying : libstdc++-devel-8.3.1-5.1.0.2.el8.x86_64 24/36
Verifying : libtool-2.4.6-25.el8.x86_64 25/36
Verifying : libxcrypt-devel-4.1.1-4.el8.x86_64 26/36
Verifying : mcelog-3:166-0.0.1.el8.x86_64 27/36
Verifying : mokutil-1:0.3.0-10.el8.x86_64 28/36
Verifying : pcp-pmda-bcc-5.1.1-3.0.1.el8.x86_64 29/36
Verifying : pcp-pmda-bpftrace-5.1.1-3.0.1.el8.x86_64 30/36
Verifying : python3-bcc-0.14.0-4.el8.x86_64 31/36
Verifying : python3-netaddr-0.7.19-8.el8.noarch 32/36
Verifying : systemtap-4.3-4.0.1.el8.x86_64 33/36
Verifying : systemtap-client-4.3-4.0.1.el8.x86_64 34/36
Verifying : systemtap-devel-4.3-4.0.1.el8.x86_64 35/36
Verifying : zlib-devel-1.2.11-16.el8_2.x86_64 36/36
Removed:
annobin-9.23-1.el8.x86_64 bcc-0.14.0-4.el8.x86_64 bcc-tools-0.14.0-4.el8.x86_64
binutils-devel-2.30-79.0.1.el8.x86_64 bpftrace-0.10.0-4.el8.x86_64 clang-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64
clang-devel-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 clang-libs-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64 clang-tools-extra-10.0.1-1.0.1.module+el8.3.0+7827+89335dbf.x86_64
cmake-filesystem-3.11.4-7.el8.x86_64 compiler-rt-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 cpp-8.3.1-5.1.0.2.el8.x86_64
gcc-8.3.1-5.1.0.2.el8.x86_64 gcc-c++-8.3.1-5.1.0.2.el8.x86_64 gcc-gdb-plugin-8.3.1-5.1.0.2.el8.x86_64
glibc-devel-2.28-127.0.1.el8.x86_64 glibc-headers-2.28-127.0.1.el8.x86_64 isl-0.16.1-6.el8.x86_64
kernel-devel-4.18.0-240.el8.x86_64 kernel-headers-4.18.0-240.el8.x86_64 kernel-uek-devel-5.4.17-2011.7.4.el8uek.x86_64
libomp-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 libomp-devel-10.0.1-1.module+el8.3.0+7827+89335dbf.x86_64 libstdc++-devel-8.3.1-5.1.0.2.el8.x86_64
libtool-2.4.6-25.el8.x86_64 libxcrypt-devel-4.1.1-4.el8.x86_64 mcelog-3:166-0.0.1.el8.x86_64
mokutil-1:0.3.0-10.el8.x86_64 pcp-pmda-bcc-5.1.1-3.0.1.el8.x86_64 pcp-pmda-bpftrace-5.1.1-3.0.1.el8.x86_64
python3-bcc-0.14.0-4.el8.x86_64 python3-netaddr-0.7.19-8.el8.noarch systemtap-4.3-4.0.1.el8.x86_64
systemtap-client-4.3-4.0.1.el8.x86_64 systemtap-devel-4.3-4.0.1.el8.x86_64 zlib-devel-1.2.11-16.el8_2.x86_64
Complete!
Note: Use the below command for Linux6/7.
# yum remove <old unused kernel>
Automatically deletion: Add or replace the value of parameter “installonly_limit” in file /etc/yum.conf which will take care of how many kernels keep after update/upgrade the system or install available kernels that depends on the value of the parameter “installonly_limit” i.e remove the old unused kernels automatically after update the system.
installonly_limit=2
[root@DBsGuruN3 ~]# cat /etc/yum.conf
[main]
gpgcheck=1
installonly_limit=2
clean_requirements_on_remove=True
best=True
skip_if_unavailable=False
List out all installed kernels in the system after removed old unused kernels.
[root@DBsGuruN3 ~]# rpm -qa | grep kernel
kernel-uek-5.4.17-2102.204.4.2.el8uek.x86_64
kernel-uek-5.4.17-2011.7.4.el8uek.x86_64
kernel-tools-4.18.0-240.el8.x86_64
kernel-tools-libs-4.18.0-240.el8.x86_64
abrt-addon-kerneloops-2.10.9-20.0.1.el8.x86_64
This document is only for learning purposes and always validate in the LAB environment first before applying in the LIVE environment.
Hope so you like this article!
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