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Message 1 of 7

NS-series Sensor memory question in NSP 9.1

Upon upgraded to 9.1, i noticed our NS sensor has 4 types of memory usage as below:

  • Flow Pool 
  • Decrypted Flow Pool 
  • Packet Buffer 
  • System Memory 

However, i noticed that even there is no any incoming traffic , the system memory of  NS sensor is higher than others memory usage type, as an example in print screen below, our NS-7300 keep showing constant system memory of 45% (the yellow dotted line) even it did not start inspecting network traffic yet.sensor.jpg

Then ,for NS-9200, the system memory showing constant 70% memory usage when there is not any traffic too. 

Is there anybody experienced this same behavior too? 

While i can understand the flow pool and decrypted flow pool, but i wonder if anyone knows what Packet Buffer and System Memory meant in memory type?




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Reliable Contributor
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Message 2 of 7

Re: NS-series Sensor memory question in NSP 9.1

Hi Dotax,

I have checked some of my NS9200's and they are all showing System memory of around 50%.

If you look at the 9.1 Manager Admin Guide it gives the below explanations,

• Packet Buffers — The percentage of the packet buffer used by the Sensor.
• System Memory — The percentage of the system memory used by the Sensor.

the example pictures show an NS7300 at about 70% and an NS9200 at about 50%. 

How long have your sensors been running? Have you tried rebooting any of them to see if the memory usage goes down?

What sensor software version are you using?


Peter Mason 

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Message 3 of 7

Re: NS-series Sensor memory question in NSP 9.1

Hi petermason,


Our sensor has been running for more than 1 month, we had start observing this system memory constant high issue previously when the sensor is in version This week monday we had upgraded it to current latest,, but it is still showing the same constant memory even we had rebooted it during the upgrade. 

I just wonder if it is normal for it to stays at around 50%? and why? This feature doesnt shows in M series sensor btw...


McAfee Retired
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Message 4 of 7

Re: NS-series Sensor memory question in NSP 9.1


Fyi,  Memory Usage on 9.1 sensors will show high under normal conditions as most of the memory is consumed by cache memory 
For ex- lets take an example 
See the below outputs 
Mem:  27665116k total, 26471300k used,  1193816k free,   100104k buffers
Swap:        0k total,        0k used,        0k free,  8750956k cached

( 8 GB is cached )

> The memory will  show high  always  as the free memory is less and most of the memory is utilized by cache memory ( 8.7 GB in above case ). 

System memory on the GUI is high as it contains cache memory as well. Cache memory can be used for future use when needed.

Free memory is less because most of the memory is utilized by cache for better results. IF cache is taking more mem, This is as per design 

As the used memory contains cache memory, hence the used memory will always be high.

Re: NS-series Sensor memory question in NSP 9.1

i Sir,

I am having same issue of high memory usage and i have five sensors on my network and they all using memory memory above 90%.Please guide me how i can reduce it or is it dangerous?

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Re: NS-series Sensor memory question in NSP 9.1

By putty into the sensor, can you show output for the command show mem-usage , if the result shows all is utilization is low (approximately less than 10%). It would be most likely due to cache memory consumption as mentioned by post above.

Re: NS-series Sensor memory question in NSP 9.1


I have putty sensor and memory usage is 0% or less then 10% on all modules.

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