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| author | Markos Fountoulakis <44345837+mfundul@users.noreply.github.com> | 2019-06-21 13:31:03 +0300 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2019-06-21 13:31:03 +0300 |
| commit | 965ae842f3bfb093349b0dfe26e34a1f05622ebb (patch) | |
| tree | 5d9dac4ee07850bb11e419497344ba701b2e5ab4 /database/engine | |
| parent | 6312080b697dd3b3415a504dd59c351815155e47 (diff) | |
Update documentation about dbengine (#6264)
* Update README.md with more up-to-date information regarding dbengine
Diffstat (limited to 'database/engine')
| -rw-r--r-- | database/engine/README.md | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/database/engine/README.md b/database/engine/README.md index fcb313d539..334f5046c7 100644 --- a/database/engine/README.md +++ b/database/engine/README.md @@ -106,4 +106,41 @@ There are explicit memory requirements **per** DB engine **instance**, meaning * An important observation is that RAM usage depends on both the `page cache size` and the `dbengine disk space` options. +## File descriptor requirements + +The Database Engine may keep a **significant** amount of files open per instance (e.g. per streaming +slave or master server). When configuring your system you should make sure there are at least 50 +file descriptors available per `dbengine` instance. + +Netdata allocates 25% of the available file descriptors to its Database Engine instances. This means that only 25% +of the file descriptors that are available to the Netdata service are accessible by dbengine instances. +You should take that into account when configuring your service +or system-wide file descriptor limits. You can roughly estimate that the netdata service needs 2048 file +descriptors for every 10 streaming slave hosts when streaming is configured to use `memory mode = dbengine`. + +If for example one wants to allocate 65536 file descriptors to the netdata service on a systemd system +one needs to edit the netdata systemd file `netdata.service` in `/lib/systemd/system` or `/usr/lib/systemd/system` +and add the line: + +``` +LimitNOFILE=65536 +``` + +in the `[Service]` section. + +For other types of services one can add the line: +``` +ulimit -n 65536 +``` +at the beginning of the service file. Alternatively you can change the system-wide limits of the kernel by changing `/etc/sysctl.conf`. For linux that would be: +``` +fs.file-max = 65536 +``` +In FreeBSD and OS X you change the lines like this: +``` +kern.maxfilesperproc=65536 +kern.maxfiles=65536 +``` +You can apply the settings by running `sysctl -p` or by rebooting. + []() |