-
You can start Netdata by executing it with
/usr/sbin/netdata
(the installer will also start it). -
You can stop Netdata by killing it with
killall netdata
. You can stop and start Netdata at any point. When exiting, the database engine saves metrics to/var/cache/netdata/dbengine/
so that it can continue when started again.
Access to the web site, for all graphs, is by default on port 19999
, so go to:
http://127.0.0.1:19999/
You can get the running config file at any time, by accessing http://127.0.0.1:19999/netdata.conf
.
In the system
directory you can find scripts and configurations for the
various distros.
The installer already installs netdata.service
if it detects a systemd system.
To install netdata.service
by hand, run:
# stop Netdata
killall netdata
# copy netdata.service to systemd
cp system/netdata.service /etc/systemd/system/
# let systemd know there is a new service
systemctl daemon-reload
# enable Netdata at boot
systemctl enable netdata
# start Netdata
systemctl start netdata
In the system directory you can find netdata-lsb
. Copy it to the proper place according to your distribution
documentation. For Ubuntu, this can be done via running the following commands as root.
# copy the Netdata startup file to /etc/init.d
cp system/netdata-lsb /etc/init.d/netdata
# make sure it is executable
chmod +x /etc/init.d/netdata
# enable it
update-rc.d netdata defaults
In the system
directory you can find netdata-openrc
. Copy it to the proper
place according to your distribution documentation.
For older versions of RHEL/CentOS that don't have systemd, an init script is included in the system directory. This can be installed by running the following commands as root.
# copy the Netdata startup file to /etc/init.d
cp system/netdata-init-d /etc/init.d/netdata
# make sure it is executable
chmod +x /etc/init.d/netdata
# enable it
chkconfig --add netdata
There have been some recent work on the init script, see PR netdata#403
You can start Netdata by running it from /etc/rc.local
or equivalent.
Normally you don't need to supply any command line arguments to netdata.
If you do though, they override the configuration equivalent options.
To get a list of all command line parameters supported, run:
netdata -h
The program will print the supported command line parameters.
The command line options of the Netdata 1.10.0 version are the following:
^
|.-. .-. .-. .-. . netdata
| '-' '-' '-' '-' real-time performance monitoring, done right!
+----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+--->
Copyright (C) 2016-2017, Costa Tsaousis <[email protected]>
Released under GNU General Public License v3 or later.
All rights reserved.
Home Page : https://my-netdata.io
Source Code: https://github.com/netdata/netdata
Wiki / Docs: https://github.com/netdata/netdata/wiki
Support : https://github.com/netdata/netdata/issues
License : https://github.com/netdata/netdata/blob/master/LICENSE
Twitter : https://twitter.com/linuxnetdata
Facebook : https://www.facebook.com/linuxnetdata/
SYNOPSIS: netdata [options]
Options:
-c filename Configuration file to load.
Default: /etc/netdata/netdata.conf
-D Do not fork. Run in the foreground.
Default: run in the background
-h Display this help message.
-P filename File to save a pid while running.
Default: do not save pid to a file
-i IP The IP address to listen to.
Default: all IP addresses IPv4 and IPv6
-p port API/Web port to use.
Default: 19999
-s path Prefix for /proc and /sys (for containers).
Default: no prefix
-t seconds The internal clock of netdata.
Default: 1
-u username Run as user.
Default: netdata
-v Print netdata version and exit.
-V Print netdata version and exit.
-W options See Advanced options below.
Advanced options:
-W stacksize=N Set the stacksize (in bytes).
-W debug_flags=N Set runtime tracing to debug.log.
-W unittest Run internal unittests and exit.
-W createdataset=N Create a DB engine dataset of N seconds and exit.
-W set section option value
set netdata.conf option from the command line.
-W simple-pattern pattern string
Check if string matches pattern and exit.
Signals netdata handles:
- HUP Close and reopen log files.
- USR1 Save internal DB to disk.
- USR2 Reload health configuration.
You can send commands during runtime via netdatacli.
Netdata uses 3 log files:
error.log
access.log
debug.log
Any of them can be disabled by setting it to /dev/null
or none
in netdata.conf
. By default error.log
and
access.log
are enabled. debug.log
is only enabled if debugging/tracing is also enabled (Netdata needs to be compiled
with debugging enabled).
Log files are stored in /var/log/netdata/
by default.
The error.log
is the stderr
of the netdata
daemon and all external plugins
run by netdata
.
So if any process, in the Netdata process tree, writes anything to its standard error,
it will appear in error.log
.
For most Netdata programs (including standard external plugins shipped by netdata), the following lines may appear:
tag | description |
---|---|
INFO |
Something important the user should know. |
ERROR |
Something that might disable a part of netdata. The log line includes errno (if it is not zero). |
FATAL |
Something prevented a program from running. The log line includes errno (if it is not zero) and the program exited. |
So, when auto-detection of data collection fail, ERROR
lines are logged and the relevant modules are disabled, but the
program continues to run.
When a Netdata program cannot run at all, a FATAL
line is logged.
The access.log
logs web requests. The format is:
DATE: ID: (sent/all = SENT_BYTES/ALL_BYTES bytes PERCENT_COMPRESSION%, prep/sent/total PREP_TIME/SENT_TIME/TOTAL_TIME ms): ACTION CODE URL
where:
ID
is the client ID. Client IDs are auto-incremented every time a client connects to netdata.SENT_BYTES
is the number of bytes sent to the client, without the HTTP response header.ALL_BYTES
is the number of bytes of the response, before compression.PERCENT_COMPRESSION
is the percentage of traffic saved due to compression.PREP_TIME
is the time in milliseconds needed to prepared the response.SENT_TIME
is the time in milliseconds needed to sent the response to the client.TOTAL_TIME
is the total time the request was inside Netdata (from the first byte of the request to the last byte of the response).ACTION
can befilecopy
,options
(used in CORS),data
(API call).
See debugging.
Netdata runs with OOMScore = 1000
. This means Netdata will be the first to be killed when your server runs out of
memory.
You can set Netdata OOMScore in netdata.conf
, like this:
[global]
OOM score = 1000
Netdata logs its OOM score when it starts:
# grep OOM /var/log/netdata/error.log
2017-10-15 03:47:31: netdata INFO : Adjusted my Out-Of-Memory (OOM) score from 0 to 1000.
Netdata will not be able to lower its OOM Score below zero, when it is started as the netdata
user (systemd case).
To allow Netdata control its OOM Score in such cases, you will need to edit netdata.service
and set:
[Service]
# The minimum Netdata Out-Of-Memory (OOM) score.
# Netdata (via [global].OOM score in netdata.conf) can only increase the value set here.
# To decrease it, set the minimum here and set the same or a higher value in netdata.conf.
# Valid values: -1000 (never kill netdata) to 1000 (always kill netdata).
OOMScoreAdjust=-1000
Run systemctl daemon-reload
to reload these changes.
The above, sets and OOMScore for Netdata to -1000
, so that Netdata can increase it via netdata.conf
.
If you want to control it entirely via systemd, you can set in netdata.conf
:
[global]
OOM score = keep
Using the above, whatever OOM Score you have set at netdata.service
will be maintained by netdata.
By default Netdata runs with the idle
process scheduling policy, so that it uses CPU resources, only when there is
idle CPU to spare. On very busy servers (or weak servers), this can lead to gaps on the charts.
You can set Netdata scheduling policy in netdata.conf
, like this:
[global]
process scheduling policy = idle
You can use the following:
policy | description |
---|---|
idle |
use CPU only when there is spare - this is lower than nice 19 - it is the default for Netdata and it is so low that Netdata will run in "slow motion" under extreme system load, resulting in short (1-2 seconds) gaps at the charts. |
other or nice |
this is the default policy for all processes under Linux. It provides dynamic priorities based on the nice level of each process. Check below for setting this nice level for netdata. |
batch |
This policy is similar to other in that it schedules the thread according to its dynamic priority (based on the nice value). The difference is that this policy will cause the scheduler to always assume that the thread is CPU-intensive. Consequently, the scheduler will apply a small scheduling penalty with respect to wake-up behavior, so that this thread is mildly disfavored in scheduling decisions. |
fifo |
fifo can be used only with static priorities higher than 0, which means that when a fifo threads becomes runnable, it will always immediately preempt any currently running other , batch , or idle thread. fifo is a simple scheduling algorithm without time slicing. |
rr |
a simple enhancement of fifo . Everything described above for fifo also applies to rr , except that each thread is allowed to run only for a maximum time quantum. |
keep or none |
do not set scheduling policy, priority or nice level - i.e. keep running with whatever it is set already (e.g. by systemd). |
For more information see man sched
.
Once the policy is set to one of rr
or fifo
, the following will appear:
[global]
process scheduling priority = 0
These priorities are usually from 0 to 99. Higher numbers make the process more important.
When the policy is set to other
, nice
, or batch
, the following will appear:
[global]
process nice level = 19
Netdata will not be able to set its scheduling policy and priority to more important values when it is started as the
netdata
user (systemd case).
You can set these settings at /etc/systemd/system/netdata.service
:
[Service]
# By default Netdata switches to scheduling policy idle, which makes it use CPU, only
# when there is spare available.
# Valid policies: other (the system default) | batch | idle | fifo | rr
#CPUSchedulingPolicy=other
# This sets the maximum scheduling priority Netdata can set (for policies: rr and fifo).
# Netdata (via [global].process scheduling priority in netdata.conf) can only lower this value.
# Priority gets values 1 (lowest) to 99 (highest).
#CPUSchedulingPriority=1
# For scheduling policy 'other' and 'batch', this sets the lowest niceness of netdata.
# Netdata (via [global].process nice level in netdata.conf) can only increase the value set here.
#Nice=0
Run systemctl daemon-reload
to reload these changes.
Now, tell Netdata to keep these settings, as set by systemd, by editing
netdata.conf
and setting:
[global]
process scheduling policy = keep
Using the above, whatever scheduling settings you have set at netdata.service
will be maintained by netdata.
On a system that is not based on systemd, to make Netdata run with nice level -1 (a little bit higher to the default for
all programs), edit netdata.conf
and set:
[global]
process scheduling policy = other
process nice level = -1
then execute this to restart netdata:
sudo service netdata restart
On a system that is based on systemd, to make Netdata run with nice level -1 (a little bit higher to the default for all
programs), edit netdata.conf
and set:
[global]
process scheduling policy = keep
edit /etc/systemd/system/netdata.service and set:
[Service]
CPUSchedulingPolicy=other
Nice=-1
then execute:
sudo systemctl daemon-reload
sudo systemctl restart netdata
You may notice that netdata's virtual memory size, as reported by ps
or /proc/pid/status
(or even netdata's
applications virtual memory chart) is unrealistically high.
For example, it may be reported to be 150+MB, even if the resident memory size is just 25MB. Similar values may be reported for Netdata plugins too.
Check this for example: A Netdata installation with default settings on Ubuntu 16.04LTS. The top chart is real memory used, while the bottom one is virtual memory:
The system memory allocator allocates virtual memory arenas, per thread running. On Linux systems this defaults to 16MB per thread on 64 bit machines. So, if you get the difference between real and virtual memory and divide it by 16MB you will roughly get the number of threads running.
The system does this for speed. Having a separate memory arena for each thread, allows the threads to run in parallel in multi-core systems, without any locks between them.
This behaviour is system specific. For example, the chart above when running Netdata on Alpine Linux (that uses musl instead of glibc) is this:
Since Netdata already uses minimal memory allocations while it runs (i.e. it adapts its memory on start, so that while
repeatedly collects data it does not do memory allocations), it already instructs the system memory allocator to
minimize the memory arenas for each thread. We have also added 2 configuration
options to allow
you tweak these settings: glibc malloc arena max for plugins
and glibc malloc arena max for netdata
.
However, even if we instructed the memory allocator to use just one arena, it seems it allocates an arena per thread.
Netdata also supports jemalloc
and tcmalloc
, however both behave exactly the
same to the glibc memory allocator in this aspect.
No, it is not.
Linux reserves real memory (physical RAM) in pages (on x86 machines pages are 4KB each). So even if the system memory allocator is allocating huge amounts of virtual memory, only the 4KB pages that are actually used are reserving physical RAM. The real memory chart on Netdata application section, shows the amount of physical memory these pages occupy(it accounts the whole pages, even if parts of them are actually used).
When you compile Netdata with debugging:
-
compiler optimizations for your CPU are disabled (Netdata will run somewhat slower)
-
a lot of code is added all over netdata, to log debug messages to
/var/log/netdata/debug.log
. However, nothing is printed by default. Netdata allows you to select which sections of Netdata you want to trace. Tracing is activated via the config optiondebug flags
. It accepts a hex number, to enable or disable specific sections. You can find the options supported at log.h. They are theD_*
defines. The value0xffffffffffffffff
will enable all possible debug flags.
Once Netdata is compiled with debugging and tracing is enabled for a few sections, the file /var/log/netdata/debug.log
will contain the messages.
Do not forget to disable tracing (
debug flags = 0
) when you are done tracing. The filedebug.log
can grow too fast.
To compile Netdata with debugging, use this:
# step into the Netdata source directory
cd /usr/src/netdata.git
# run the installer with debugging enabled
CFLAGS="-O1 -ggdb -DNETDATA_INTERNAL_CHECKS=1" ./netdata-installer.sh
The above will compile and install Netdata with debugging info embedded. You can now use debug flags
to set the
section(s) you need to trace.
We have made the most to make Netdata crash free. If however, Netdata crashes on your system, it would be very helpful to provide stack traces of the crash. Without them, is will be almost impossible to find the issue (the code base is quite large to find such an issue by just objerving it).
To provide stack traces, you need to have Netdata compiled with debugging. There is no need to enable any tracing
(debug flags
).
Then you need to be in one of the following 2 cases:
-
Netdata crashes and you have a core dump
-
you can reproduce the crash
If you are not on these cases, you need to find a way to be (i.e. if your system does not produce core dumps, check your distro documentation to enable them).
you need to have Netdata compiled with debugging info for this to work (check above)
Run the following command and post the output on a github issue.
gdb $(which netdata) /path/to/core/dump
you need to have Netdata compiled with debugging info for this to work (check above)
Install the package valgrind
and run:
valgrind $(which netdata) -D
Netdata will start and it will be a lot slower. Now reproduce the crash and valgrind
will dump on your console the
stack trace. Open a new github issue and post the output.