Merge commit '1a922025' into release-5.0-reverted-222

guide/ops/troubleshooting/increase-system-resource-limits.md

@@ -9,10 +9,7 @@ If you encounter the following error:
     Caused by: java.io.IOException: Too many open files
             at java.io.UnixFileSystem.createFileExclusively(Native Method)[:1.8.0
 
-Please check the limit for opened files `cat /proc/sys/fs/file-max` and increase it.
-You can increase the maximum limit of opened files by setting `fs.file-max` in `/etc/sysctl.conf`.
-and then running `sudo sysctl -p` to apply the changes.
-
+Please check and increase the limit for opened files.
 
 If you encounter the error below, e.g. when running with many entities, please consider **increasing the ulimit**:
 
@@ -21,6 +18,42 @@ If you encounter the error below, e.g. when running with many entities, please c
 On the VM running Apache Brooklyn, it is recommended that nproc and nofile are reasonably high 
 (e.g. 16384 or higher; a value of 1024 is often the default).
 
+## For Centos 7
+To check the current limits, you will need to know the PID for the brooklyn process. You can find
+this by running `systemctl status brooklyn` and checking the `Main PID` line.
+
+To see the current limits, run `cat /proc/<brooklyn PID>/limits` replacing <brooklyn PID> with the Main PID
+from above
+
+To override the default limits, you will need to create a `limits.conf` and populate it with the required
+values as follows:
+
+```
+mkdir -p /etc/systemd/system/brooklyn.service.d
+
+cat > /etc/systemd/system/brooklyn.service.d/limits.conf << EOF
+[Service]
+LimitNOFILE=16384
+LimitNPROC=16384
+EOF
+```
+
+You will then need to reload the systemctl daemon and restart brooklyn:
+
+```
+systemctl daemon-reload
+systemctl restart brooklyn
+```
+
+To check the new limits, you will need to obtain the new brooklyn PID by running `systemctl status brooklyn`
+and `cat`ing the process limits as above
+
+
+## For Centos 6
+Please check the limit for opened files `cat /proc/sys/fs/file-max` and increase it.
+You can increase the maximum limit of opened files by setting `fs.file-max` in `/etc/sysctl.conf`.
+and then running `sudo sysctl -p` to apply the changes.
+
 If you want to check the current limits run `ulimit -a`. Alternatively, if Brooklyn is run as a 
 different user (e.g. with user name "brooklyn"), then instead run `ulimit -a -u brooklyn`.