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Crashkernel is a special feature in CentOS which helps to reserve a copy of the memory thereby enabling debug of the kernel whenever a crash occurs. This feature is enabled by default on CentOS. However , the kernel hardly crashes and it uses a portion of the memory. This used memory remains unused by any other application in system.

 

To see if this feature is enabled, you can use the command below to check;


dmesg | grep Reserving

 

If it is actually enabled, you will get a message acknowledging that.

 

Since the kernel hardly crash , it is recommended that the crashkernel feature is disabled in order to make the memory it uses usable and this is more ideal.

 

You can disable it by using the command below;

 

sed -i 's/crashkernel=auto/crashkernel=no/' /etc/default/grub
grub2-mkconfig -o /boot/grub2/grub.cfg

 

 

After disabling it, you should reboot the system by using the command below;

 

reboot

 

 

After the rebooting process is successful, you can recheck the status of the crashkernel by using the command below;

 

dmesg | grep Reserving

 

Now you will not get an output!

 

 

Finally , you can confirm the free memory available and you would see that you now have more memory available. Check the free memory by using the command below;


free -m

 

 

Conclusion

You can see how easy it is to disable the crashkernel to save more memory for the system. You can consult our Server Experts for support regarding your Server.


Conclusion