Nagios Support Forum

RAM, and the proper tuning of NLS Java heaps, is critical the proper running of a large NLS cluster. If anything else, if you can throw more memory at it, it will run better.

Somebody is watching the clock

Heheh. Trevor gets mad at me when I do that, but it's still fun.

*ahem* On-topic, please.

hsmith wrote:Shouldn't be. How much RAM does your server have?

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free -m

[root@fikc-naglsprod01 ~]# free -m
total used free shared buffers cached
Mem: 7994 7187 806 0 142 1100
-/+ buffers/cache: 5944 2049
Swap: 255 36 219
[root@fikc-naglsprod01 ~]#

- should we increase SWAP ?

If you have the ability to increase physical memory (I do not know if this is a virtual machine or a physical machine), that will help more than increasing swap. As a general rule, swapping to disk is 100 times slower than dealing with RAM, so you want to avoid it if possible.

By default, NLS allocates 50% of available system RAM to elasticsearch. You can verify this in /etc/sysconfig/elasticsearch. It MAY be worthwhile to increase the ES_HEAP_SIZE to something bigger than 50% of RAM. You can test this out by changing the last line in this code: to Which will allocate 5G of RAM instead of ~4G of RAM to elasticsearch's Java heap. This might work. You might be good to go as far as 6114m, which would be 6GB, but I wouldn't push it any farther than that on a system with 8GB of RAM. Increasing swap will likely not gain you anything on this system.

A good article on elasticsearch JVM tuning can be found at https://www.elastic.co/guide/en/elastic ... izing.html

Definitely agreed, especially on a system like NLS that likes a lot of RAM, swapping to disk is one of the worst things you can do for your performance.

eloyd wrote:If you have the ability to increase physical memory (I do not know if this is a virtual machine or a physical machine), that will help more than increasing swap. As a general rule, swapping to disk is 100 times slower than dealing with RAM, so you want to avoid it if possible.

By default, NLS allocates 50% of available system RAM to elasticsearch. You can verify this in /etc/sysconfig/elasticsearch. It MAY be worthwhile to increase the ES_HEAP_SIZE to something bigger than 50% of RAM. You can test this out by changing the last line in this code:

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# Heap Size (defaults to 256m min, 1g max)
# Nagios Log Server Default to 0.5 physical Memory
ES_HEAP_SIZE=$(expr $(free -m|awk '/^Mem:/{print $2}') / 2 )m

to

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ES_HEAP_SIZE=5120m

Which will allocate 5G of RAM instead of ~4G of RAM to elasticsearch's Java heap. This might work. You might be good to go as far as 6114m, which would be 6GB, but I wouldn't push it any farther than that on a system with 8GB of RAM. Increasing swap will likely not gain you anything on this system.

A good article on elasticsearch JVM tuning can be found at https://www.elastic.co/guide/en/elastic ... izing.html

Increased HEAP as advised and reboot the server.
- works well, going to keep in mind RAM increases

We could now close this support thread

Glad I could help!