# Before Install

You MUST set up your environment according to the steps below before installing Fluentd. Failing to do so will be the cause of many unnecessary problems.

## Set Up NTP

It's HIGHLY recommended that you set up NTP daemon (e.g. [*chrony*](https://chrony.tuxfamily.org/), *ntpd*, etc) on the node to have accurate current timestamp. This is crucial for the production-grade logging services. For AWS (Amazon Web Services) users we recommend to use Amazon Time Sync Service, AWS hosted NTP server. Please check [AWS EC2: Setting the Time for Your Linux Instance](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/set-time.html).

## Increase Max # of File Descriptors

Please increase the maximum number of file descriptors. You can check the current number using the `ulimit -n` command.

```
$ ulimit -n
65535
```

If your console shows `1024`, it is insufficient. Please add following lines to your `/etc/security/limits.conf` file and reboot your machine.

```
root soft nofile 65536
root hard nofile 65536
* soft nofile 65536
* hard nofile 65536
```

This `65536` is safer value for large deployment. The required number of file descriptors depends on your fluentd plugins and setting. Here are the estimation examples:

* in\_tail: The number of watching files
* in\_forward: The number of incoming access
* buf\_file: The number of buffer chunks. It is configured via [buffer parameters](https://docs.fluentd.org/0.12/articles/broken-reference)
* output: The used file descriptors are less than others. Temporary

  file for upload, connection pooling in the client library, etc

## Optimize Network Kernel Parameters

For high load environments consisting of many Fluentd instances, please add these parameters to your `/etc/sysctl.conf` file. Please either type `sysctl -p` or reboot your node to have the changes take effect.

```
net.core.somaxconn = 1024
net.core.netdev_max_backlog = 5000
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
net.ipv4.tcp_wmem = 4096 12582912 16777216
net.ipv4.tcp_rmem = 4096 12582912 16777216
net.ipv4.tcp_max_syn_backlog = 8096
net.ipv4.tcp_slow_start_after_idle = 0
net.ipv4.tcp_tw_reuse = 1
net.ipv4.ip_local_port_range = 10240 65535
```

These kernel options were originally taken from the presentation "[How Netflix Tunes EC2 Instances for Performance](https://www.slideshare.net/brendangregg/how-netflix-tunes-ec2-instances-for-performance)" by [Brendan Gregg](http://www.brendangregg.com/), Senior Performance Architect at AWS re:Invent 2017.

If this article is incorrect or outdated, or omits critical information, please [let us know](https://github.com/fluent/fluentd-docs-gitbook/issues?state=open). [Fluentd](http://www.fluentd.org/) is a open source project under [Cloud Native Computing Foundation (CNCF)](https://cncf.io/). All components are available under the Apache 2 License.