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130 lines
6.2 KiB
Markdown
130 lines
6.2 KiB
Markdown
source: Support/Performance.md
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path: blob/master/doc/
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# Performance optimisations
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This document will give you some guidance on optimising your setup.
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The suggestions are in a rough order of how much impact they will have.
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### RRDCached
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**We absolutely recommend running this, it will save on IO load**. [RRDCached](http://docs.librenms.org/Extensions/RRDCached/)
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### MySQL Optimisation
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It's advisable after 24 hours of running MySQL that you run [MySQL Tuner](https://raw.githubusercontent.com/major/MySQLTuner-perl/master/mysqltuner.pl)
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which will make suggestions on things you can change specific to your setup.
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One recommendation we can make is that you set the following in my.cnf under a [mysqld] group:
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```bash
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innodb_flush_log_at_trx_commit = 0
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```
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You can also set this to 2. This will have the possibility that you could lose up to 1 second on mysql data in the event
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MySQL crashes or your server does but it provides an amazing difference in IO use.
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### Polling modules
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Review the graph of poller module time take under gear > pollers > performance to see what modules are consuming poller time.
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This data is shown per device under device > graphs > poller.
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Disable polling (and discovery) modules that you do not need. You can do this globally in `config.php` like:
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Disable OSPF polling
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```php
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$config['poller_modules']['ospf'] = false;
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```
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You can disable modules globally then re-enable the module per device or the opposite way. For a list of modules please see
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[Poller modules](http://docs.librenms.org/Support/Poller%20Support/)
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### SNMP Max Repeaters
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We have support for SNMP Max repeaters which can be handy on devices where we poll a lot of ports or bgp sessions for instance and
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where snmpwalk or snmpbulkwalk is used. This needs to be enabled on a per device basis under edit device -> snmp -> Max repeaters.
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You can also set this globally with the config option `$config['snmp']['max_repeaters'] = X;`.
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It's advisable to test the time taken to snmpwalk IF-MIB or something similar to work out what the best value is. To do this run the following
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but replace <REPEATERS> with varying numbers from 10 upto around 50. You will also need to set the correct snmp version, hostname and community string:
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`time snmpbulkwalk -v2c -cpublic HOSTNAME -Cr<REPEATERS> -M /opt/librenms/mibs -m IF-MIB IfEntry`
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> NOTE: Do not go blindly setting this value as you can impact polling negatively.
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### SNMP Max OIDs
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For sensors polling we now do bulk snmp gets to speed things up. By default this is ten but you can overwrite this per device under
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edit device -> snmp -> Max OIDs.
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You can also set this globally with the config option `$config['snmp']['max_oid'] = X;`.
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> NOTE: It is advisable to monitor sensor polling when you change this to ensure you don't set the value too high.
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### fping tuning
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You can change some of the default fping options used globally or per device. The defaults are:
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```php
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$config['fping_options']['timeout'] = 500;
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$config['fping_options']['count'] = 3;
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$config['fping_options']['interval'] = 500;
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```
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If your devices are slow to respond then you will need to increase the timeout value and potentially the interval value.
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However if your network is stable, you can increase poller performance by dropping the count value to 1 and/or the timeout+millsec value to 200 or 300:
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```php
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$config['fping_options']['timeout'] = 300;
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$config['fping_options']['count'] = 1;
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$config['fping_options']['interval'] = 300;
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```
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This will mean that we no longer delay each icmp packet sent (we send 3 in total by default) by 0.5 seconds. With only 1 icmp packet
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being sent then we will receive a response quicker. The defaults mean it will take at least 1 second for a response no matter how
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quick the icmp packet is returned.
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### Optimise poller-wrapper
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The default 16 threads that `poller-wrapper.py` runs as isn't necessarily the optimal number. A general rule of thumb is
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2 threads per core but we suggest that you play around with lowering / increasing the number until you get the optimal value.
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**Note** KEEP in MIND that this doesn't always help, it depends on your system and CPU. So be careful.
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This can be changed by going to the cron job for librenms. Usually in `/etc/cron.d/librenms` and changing the "16"
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```
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*/5 * * * * librenms /opt/librenms/cronic /opt/librenms/poller-wrapper.py 16
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```
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### Recursive DNS
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If your install uses hostnames for devices and you have quite a lot then it's advisable to setup a local recursive dns instance on the
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LibreNMS server. Something like pdns-recursor can be used and then configure `/etc/resolv.conf` to use 127.0.0.1 for queries.
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### Per port polling - experimental
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By default the polling ports module will walk ifXEntry + some items from ifEntry regardless of the port. So if a port is marked as deleted because you don't want to see them
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or it's disabled then we still collect data. For the most part this is fine as the walks are quite quick. However for devices with a lot of ports and good % of those are
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either deleted or disabled then this approach isn't optimal. So to counter this you can enable 'selected port polling' per device within the edit device -> misc section or by
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globally enabling it (**not recommended**): `$config['polling']['selected_ports'] = true;`. You can also set it for a specific OS: `$config['os']['ios']['polling']['selected_ports'] = true;`.
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Running `./scripts/collect-port-polling.php` will poll your devices with both full and selective polling, display a table with the difference and optionally enable or disable selected ports polling for devices which would benefit from a change.
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Note that it doesn't continously re-evaluate this, it will only be updated when the script is run. There are a number of options:
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```
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-h <device id> | <device hostname wildcard> Poll single device or wildcard hostname
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-e <percentage> Enable/disable selected ports polling for devices which would benefit <percentage> from a change
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```
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### Web interface
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#### HTTP/2
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If you are running https then you should enable http/2 support in whatever web server you use:
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For Nginx (1.9.5 and above) change `listen 443 ssl;` to `listen 443 ssl http2;` in the Virtualhost config.
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For Apache (2.4.17 an above) set `Protocols h2 http/1.1` in the Virtualhost config.
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