How to clear RAM without rebooting?

David Beroff · Jun 19, 2018

I want to free up memory by clear RAM on my VPS Linux but seem this needs a reboot. Can I clear RAM without rebooting?

Malware.Expert · Jun 19, 2018

With root account:

Code:

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

Clear PageCache, dentries and inodes

But not recommend production server's, just Clear PageCache:

Code:

sync; echo 1 > /proc/sys/vm/drop_caches

AlbaHost · Jun 19, 2018

David Beroff said:
I want to free up memory by clear RAM on my VPS Linux but seem this needs a reboot. Can I clear RAM without rebooting?

Just add to crontab:

*/10 * * * * sync && echo 3 > /proc/sys/vm/drop_caches

Let the cron do the job for you, you can change time, mentined is in every 10 minutes.

David Beroff · Jun 19, 2018

Malware.Expert said:
With root account:

Code:

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

Clear PageCache, dentries and inodes
But not recommend production server's, just Clear PageCache:

Code:

sync; echo 1 > /proc/sys/vm/drop_caches

I tried to run this command on a small VPS and seem it worked

Before purge RAM

Code:

[root@server1 ~]# free -m
             total       used       free     shared    buffers     cached
Mem:           971        794        177          0        237        432
-/+ buffers/cache:        124        847
Swap:            0          0          0

Code:

[root@server1 ~]# sync; echo 3 > /proc/sys/vm/drop_caches

After purged RAM

Code:

[root@server1 ~]# free -m
             total       used       free     shared    buffers     cached
Mem:           971         96        875          0          0         14
-/+ buffers/cache:         80        891
Swap:            0          0          0

and this command deleted cached of VPS, right?

cached 432 -> cached 14

mobin · Jun 20, 2018

I am just wondering what advantage do you see after clearing the cached contents from RAM? Seeing a lot of Free memory is not really shows its all good, especially when its showing after clearing the cache. Clearing cache will free RAM, but it causes the kernel to look for files on the disk rather than in the cache which can cause performance issues. So its not recommended to do it regularly. When there is an increased demand for memory kernel will automatically clear cache and allocate RAM for the requested process.

David Beroff · Jun 20, 2018

mobin said:
I am just wondering what advantage do you see after clearing the cached contents from RAM?

Sometime server high load then it is time to clear RAM?

mobin said:
So its not recommended to do it regularly.

So when should we clear RAM?

mobin said:
Clearing cache will free RAM, but it causes the kernel to look for files on the disk rather than in the cache which can cause performance issues.

I am caring about this and I should ignore purging RAM and caches on servers?

panamaserver · Jun 24, 2018

if your server is getting low RAM you need to find the reason, clearing ram is not the solution
if you have added more websites to your server
or if you have added some plugins to a site
or any modification you have made that cause the server to use all the RAM need to be considered.

Once you find the reason you probably can fix it or optimize it, or BUY more ram maybe that's what your server need because you have added more sites or your sites grow in traffic considerably.

Daniel204 · Jun 25, 2018

Hi,

If you have a suitable motherboard and an OS that supports hotpluggable RAM (such as Linux), yes.

If you're not running a motherboard and OS that supports such RAM (ie: most people), the answer is no.

HTH!

Regards,
Daniel

Nixtree · Jun 28, 2018

In your case I will say if possible please try adding a 2 G swap which will help in load times. Normally there is no actual use in clearing the RAM as those which are showed as cached is also available for processes. So it will get cached again after some minutes or hours.

How to clear RAM without rebooting?

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