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Monthly Archives / August 2015

  • Aug 21 / 2015
  • 0
Linux

Clear cache memory on Linux Systems

Sometimes, you can see that memory is not correctly released once used and some caching can remain.

You can see that by using the free command:

# free -m
             total       used       free     shared    buffers     cached
Mem:         64458      53397      11060          0       1550      49163
-/+ buffers/cache:       2683      61774
Swap:         9998         35       9963

At this time, you can so free this cache and release memory by using this command:

# sync; echo 3 > /proc/sys/vm/drop_caches

Now, you can check again:

# free -m
             total       used       free     shared    buffers     cached
Mem:         64458       1162      63295          0          1         32
-/+ buffers/cache:       1128      63329
Swap:         9998         35       9963

The memory has correctly been released and the cache is almost empty!

  • Aug 03 / 2015
  • 0
Linux

Change OVH linux kernel to a standard one

OVH servers come with a custom kernel provided by OVH. This kernel is compiled with a lots of functions deactivated like:

  • Virtualization components
  • Modules support

If you need those features, you will probably need to install a standard kernel not provided by OVH. For that, just follow the instructions below.

  • Install a standard linux kernel for Ubuntu (or any other distribution, but you’ll need to adapt commands):
apt-get install linux-image-server
  • Change boot order by adding a lower priority to the OVH one:
mv /etc/grub.d/06_OVHkernel /etc/grub.d/25_OVHkernel
  • Reload grub configuration on your system:
update-grub
  • Restart the server so it can restart on new kernel freshly installed:
reboot

Now, after reboot, you should see your new kernel loaded by typing the following command:

uname -r

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