How does ganglia work

Here is more about the function of ganglia in the body. Think of ganglia as the relay stations of the body's nervous system: As one nerve enters a ganglion, another nerve exits it. Ganglia play an essential role in connecting the parts of the peripheral and central nervous systems.

Motor ganglia receive information from the central nervous system to regulate and control involuntary movements and functions. Involuntary functions include those of organs such as the heart and lungs. Motor ganglia also send information to the central nervous system from these organs. Sensory ganglia, or dorsal root ganglia, send sensory information to the central nervous system.

This information includes touch, smell, taste, sound, and visual stimuli. They also deliver information about body position and sensory feedback relating to organs. For example, if your stomach hurts, the sensory neurons of the peripheral nervous system are sending a message through the sensory ganglia to your central nervous system that something is not right.

Conditions or injuries that may affect the basal ganglia include:. The following conditions are known to affect the basal ganglia in the brain and voluntary movement:. Unsurprisingly, conditions or injuries involving the basal ganglia are extremely serious and often lead to permanent disability or death. Damage to other ganglia throughout the body can also cause problems. For example, glaucoma is the result of vision-related ganglia damage.

Similarly, an injury to the dorsal root ganglia in the spine, such as spinal vertebrae compression, can cause sensory issues, like tingling in the feet.

Conditions that affect the peripheral nervous system may impact ganglia. Damage to the peripheral nervous system can happen due to:. Treatment is different depending on the cause of ganglia damage. It also depends on which ganglia have been damaged. Some causes of basal ganglia damage, for instance, are reversible and respond well to rehabilitation.

Treatments are also available for heavy metal poisoning. Depending on the individual, there may not be any lingering symptoms after treatment. Degenerative diseases that affect ganglia in the peripheral nervous system may not be treatable. People with severe head trauma that impacts the basal ganglia may not recover. If they do, they may end up with a permanent disability.

Sign up for our Health Tip of the Day newsletter, and receive daily tips that will help you live your healthiest life. McGill University. The motor cortex. Basal ganglia dysfunction. January 5, Name your grid in the grid section by uncommenting the gridname line and replacing MyGrid with the grid name of your choice.

In this example, we will name the grid London. Update the name for the cluster, and then add host and port information for each server you want to add to that cluster. For instance, in the example below, we are adding two clusters, called Servers and Databases , to the London grid. All of the nodes in Servers are using port , and all of the nodes in Databases are using port On each server or node specified in the Gmetad configuration file in this example, localhost, 1.

Update the name value in the cluster section to match the cluster name. Make sure to update the port number!

In our example, since this is part of the Databases cluster, the port should be The other lines can stay the same. Restart Ganglia-monitor, Gmetad and Apache on the Ganglia host server or master node. In the web interface, you should now see the name of your grid, and the option to choose a cluster. From there you can select and drill down into a node. Ganglia is very easy to set up and scale up from one node to hundreds or thousands.

It features a high performance level and can help you monitor as many servers as you need. Where would you like to share this to? Twitter Reddit Hacker News Facebook. Share link Tutorial share link.

Sign Up. DigitalOcean home. Community Control Panel. Hacktoberfest Contribute to Open Source. By Scott Lee Published on August 5, Introduction Ganglia is a scalable distributed monitoring system. On the back end, Ganglia is made up of the following components: Gmond Ganglia monitoring daemon : a small service that collects information about a node. This is installed on every server you want monitored.

Gmetad Ganglia meta daemon : a daemon on the master node that collects data from all the Gmond daemons and other Gmetad daemons, if applicable. RRD Round Robin Database tool: a tool on the master node used to store data and visualizations for Ganglia in time series. PHP web front-end: a web interface on the master node that displays graphs and metrics from data in the RRD tool. Prerequisites You will need: One master node Droplet running Ubuntu This is the node you will use to view all of the monitoring data.

At least one additional node that you want to monitor, running Ubuntu However, you can easily complete the tutorial with just one node on each cluster. Next, grant the user sudo privileges with the visudo command. Client Installation On the second node you want to monitor in the my cluster cluster, install the Ganglia monitor.

Repeat these steps on any other nodes you want to monitor in this cluster. Grids Grids allow you to organize several clusters together. The name of this Grid. It has multiple purposes:. Figure shows how gweb search autocomplete allows you to find metrics across your entire deployment.

To use this feature, click on the Search tab and start typing in the search field. Once you stop typing, a list of results will appear. Results will contain:. A list of matching metrics. If the search term matches metrics on multiple hosts, all hosts will be shown. Click on any of the links and a new window will open that will take you directly to the result.

You can keep clicking on the results; for each result, a new window will open. Views are an arbitrary collection of metrics, host report graphs, or aggregate graphs. They are intended to be a way for a user to specify things of which they want to have a single overview. For example, a user might want to see a view that contains aggregate load on all servers, aggregate throughput, load on the MySQL server, and so on. To create views click the Views tab, then click Create View.

Type your name, then click Create. Click the plus sign above or below each metric or composite graph; a window will pop up in which you can select the view you want the metric to be added.

Optionally, you can specify warning and critical values. Those values will appear as vertical lines on the graph.

Repeat the process for consecutive metrics. Figure shows the UI for adding a metric to a view. You can change that by specifying an alternate directory in conf. You can create or edit existing files. It must be unique. Here is an example definition of a view that will result with a view with three different graphs:. Table lists the top-level attributes for the JSON view definition. Each item can have the attributes listed in Table This command will report any issues. Aggregate graphs Figure allow you to create composite graphs combining different metrics.

At a minimum, you must supply a host regular expression and metric regular expression. This is an extremely powerful feature, as it allows you to quickly and easily combine all sorts of metrics. Figure includes two aggregate graphs showing all metrics matching host regex of loc and metric regex of load.

Related to aggregate graphs are decompose graphs, which decompose aggregate graphs by taking each metric and putting it on a separate graph. This feature is useful when you have many different metrics on an aggregate graph and colors are blending together.

You will find the Decompose button above the graph. The compare hosts feature allows you to compare hosts across all their matching metrics. It will basically create aggregate graphs for each metric. This feature is helpful when you want to observe why a particular host or hosts is behaving differently than other hosts. They are useful in providing visual cues when certain events happen.

For example, you might want to overlay software deploys or backup jobs so that you can quickly associate change in behavior on certain graphs to an external event, as in Figure In this example, we wanted to see how increased rrdcached write delay would affect our CPU wait IO percentage, so we added an event when we made the change. Alternatively, you can overlay a timeline to indicate the duration of a particular event. For example, Figure shows the full timeline for a backup job. This is an example JSON hash:.

It is also possible to use a different backend for events, which can be useful if you need to scale up to hundreds or thousands of events without incurring the processing penalty associated with JSON parsing.

To add an event from your cron job, execute a command such as:. Automatic rotation is a feature intended for people in data centers who need to continuously rotate metrics to help spot early signs of trouble.

It is intended to work in conjunction with views. To activate it, click Automatic Rotation and then select the view you want rotated. Metrics will be rotated until the browser window is closed.

You can change the view while the view is rotated; changes will be reflected within one full rotation. Graphs rotate every 30 seconds by default. You can adjust the rotation delay in the GUI. Another powerful aspect of automatic rotation is that if you have multiple monitors, you can invoke different views to be rotated on different monitors.

It is intended for any mobile browsers supported by the jQueryMobile toolkit. The mobile view contains only a subset of features, including views optimized for a small screen, host view, and search.

Defining graphs via PHP is more complex but gives you complete control over every aspect of the graph. See the example PHP report for more details. For typical use cases, JSON is definitely the easiest way to configure graphs. For example, consider the following JSON snippet, which will create a composite graph that shows all load indexes as lines on one graph:.

To use this snippet, save it as a file and put it in the graph. There are two main sections to the JSON report. The first is a set of configurations for the overall report, and the second is a list of options for the specific data series that you wish to graph.

The configuration options passed to the report are shown in Table Options for series array are listed in Table Note that each series has its own instance of the different options. Once you compose your graphs, it is often useful to validate JSON. One example would be to verify that there are no extra commas, etc. There are a number of features in gweb that are turned off by default or can be adjusted:. By default, when you click on a host view, all of the metric groups are expanded.

You can change this view so that only metric graph titles are shown and you have to click on the metric group to expand the view. To make this collapsed view the default behavior, add the following setting to conf. Note that the aggregate graphs will still include data from all hosts, including those not displayed due to filters. The host and cluster view will refresh every 5 minutes seconds. To adjust it, set the following value in conf.