Network Management

Reply
Contributor II

swap memory usage on airwave

Hello community:

 

since January 2018, my swap is reaching its maximum capacity, why does it happen? reports are taking to long to be generated. could it be the cause of full swap?

 

[root@localhost ~]# free -m
             total       used       free     shared    buffers     cached
Mem:         32057      31825        232       2753         40       3190
-/+ buffers/cache:      28594       3463
Swap:         4095       4095          0

Re: swap memory usage on airwave

For a healthy Linux box Swap is typically not a concern. The only concern we should have is if total used memory - (buffers + cache) is greater than the total memory. In your scenario,

[root@localhost ~]# free -m
             total       used       free     shared    buffers     cached
Mem:         32057      31825        232       2753         40       3190
-/+ buffers/cache:      28594       3463
Swap:         4095       4095          0

31825/32057 is used, but if you remove buffers/cache, only 28594/32057 is used. 

Swap would have been got used at some point of time and if we have enough free RAM we dont have to be concerned of this, this should eventually come down or we can manually clear it.
There is a Linux kernel parameter known as Swappiness which determines how a Linux system will use swap space: http://en.wikipedia.org/wiki/Swappiness

By default, including on AirWave, this is set to 60. A value of 0 means swap will only be used if there no available memory, meaning the total used memory - (buffers + cache) has exceeded the available memory on the system. A value of 100 indicates that the kernel will attempt to swap any inactive memory pages to disk as often as possible. There is a drawback to setting this value too low or too high as explained in the Wikipedia article.

What this means for AirWave is that customers will see swap being used regularly if their system is active, even if they have more than adequate free memory available.

Below KB link should have more explanation on this,

https://community.arubanetworks.com/t5/Monitoring-Management-Location/How-does-AirWave-use-memory-and-swap-space-and-when-is-it-a/ta-p/179984

You can also get the help of TAC to check the overall health of the server and set appropriate swappiness value.


Regards,
Vishnu
If my post helped you, don't forget to give kudos ;)
Search Airheads
cancel
Showing results for 
Search instead for 
Did you mean: