Add page on troubleshooting systemd permissions

content/influxdb/v1.8/troubleshooting/systemd.md

@@ -0,0 +1,33 @@
+---
+title: Troubleshoot systemd errors
+list_title: systemd permission errors
+description: Troubleshoot errors with InfluxDB and systemd permissions
+menu:
+  platform:
+    name: systemd errors
+    parent: Troubleshoot
+    weight: 1
+---
+
+When running InfluxDB using systemd (Ubuntu, Debian, CentOS), you might encounter errors in the InfluxDB logs (via `journalctl -u influxdb`) like:
+
+- `error msg="Unable to open series file"`
+- `run: open server: open tsdb store: mkdir /var/lib/influxdb/data/_internal/_series/00: permission denied`
+
+When InfluxDB is installed with systemd, an `influxdb` user and group is automatically created.
+If the user runs an `influxd` process directly from their login shell, it can generate new series files not accessible by the `influxdb` user.
+In this case, when systemd starts the InfluxDB service (via `sudo systemctl start influxdb`),
+the InfluxDB process will exit because it cannot access the leftover files owned by the `root` user.
+
+To resolve this issue, set all files in the InfluxDB directories to be owned by the `influxdb` user and group.
+Run the following command:
+
+```
+sudo chown -R influxdb:influxdb /var/lib/influxdb/*
+```
+
+Alternatively, if the data is not important, reset the database by removing all files:
+
+```
+sudo rm -rf /var/lib/influxdb/
+```