Frequently Asked Questions

How can I contact the developers?

The best place to discuss PMM with developers and other community members is the community forum.

If you would like to report a bug, use the PMM project in JIRA.

What are the minimum system requirements for PMM?

PMM Server

Any system which can run Docker version 1.12.6 or later.

It needs roughly 1 GB of storage for each monitored database node with data retention set to one week.

Note

By default, retention is set to 30 days for Metrics Monitor and for Query Analytics. Also consider disabling table statistics, which can greatly decrease Prometheus database size.

Minimum memory is 2 GB for one monitored database node, but it is not linear when you add more nodes. For example, data from 20 nodes should be easily handled with 16 GB.

PMM Client

Any modern 64-bit Linux distribution. It is tested on the latest versions of Debian, Ubuntu, CentOS, and Red Hat Enterprise Linux.

Minimum 100 MB of storage is required for installing the PMM Client package. With good constant connection to PMM Server, additional storage is not required. However, the client needs to store any collected data that it is not able to send over immediately, so additional storage may be required if connection is unstable or throughput is too low.

How to control data retention for PMM?

By default, both Prometheus and QAN store time-series data for 30 days.

Depending on available disk space and your requirements, you may need to adjust data retention time.

You can control data retention by the following way.

  1. Select the PMM Settings dashboard in the main menu.

    _images/pmm-add-instance.png

    Choosing the PMM Settings menu entry

  2. In the Settings section, enter new data retention value in days.

    _images/pmm.settings_settings.png

    Entering data retention on the Settings dashboard

  3. Click the Apply changes button.

How often are nginx logs in PMM Server rotated?

PMM Server runs logrotate to rotate nginx logs on a daily basis and keep up to 10 latest log files.

Can I monitor multiple service instances?

Yes, you can add multiple instances of MySQL or some other service to be monitored from one PMM Client. In this case, you will need to provide a distinct port and socket for each instance, and specify a unique name for each instance (by default, it uses the name of the PMM Client host).

For example, if you are adding complete MySQL monitoring for two local MySQL servers, the commands could look similar to the following:

$ sudo pmm-admin add mysql --username root --password root instance-01 127.0.0.1:3001
$ sudo pmm-admin add mysql --username root --password root instance-02 127.0.0.1:3002

For more information, run

$ pmm-admin add mysql --help

Can I rename instances?

You can remove any monitoring instance as described in Removing monitoring services with pmm-admin remove and then add it back with a different name.

When you remove a monitoring service, previously collected data remains available in Grafana. However, the metrics are tied to the instance name. So if you add the same instance back with a different name, it will be considered a new instance with a new set of metrics. So if you are re-adding an instance and want to keep its previous data, add it with the same name.

Can I add an AWS RDS MySQL or Aurora MySQL instance from a non-default AWS partition?

By default the RDS discovery works with the default aws partition. But you can switch to special regions, like the GovCloud one, with the alternative AWS partitions (e.g. aws-us-gov) adding them to the Settings via the PMM Server API:

_images/aws-partitions-in-api.png

You can specify any of them instead of the aws default value, or use several of them, with the JSON Array syntax: ["aws", "aws-cn"].

How to troubleshoot communication issues between PMM Client and PMM Server?

Broken network connectivity may be caused by rather wide set of reasons. Particularly, when using Docker, the container is constrained by the host-level routing and firewall rules. For example, your hosting provider might have default iptables rules on their hosts that block communication between PMM Server and PMM Client, resulting in DOWN targets in Prometheus. If this happens, check firewall and routing settings on the Docker host.

Also PMM is able to generate a set of diagnostics data which can be examined and/or shared with Percona Support to solve an issue faster. You can get collected logs from PMM Client using the pmm-admin summary command.

The logs archive obtained in this way includes PMM Client logs and also logs which were received from the PMM Server, stored separately in the client and server folders. The server folder also contains its own client subfolder with the self-monitoring client information collected on the PMM Server.

Note

Starting from PMM 2.4.0 there is an additional flag that allows to fetch pprof debug profiles and add them to the diagnostics data. To do it, run pmm-admin summary --pprof.

Obtaining logs from PMM Server can be done by specifying the ``https://<address-of-your-pmm-server>/logs.zip` URL, or by clicking the server logs link on the Prometheus dashboard:

_images/get-logs-from-prometheus-dashboard.png

The logs archive obtained in this way includes diagnostics information gathered from the PMM Server, and the client subfolder with the self-monitoring client information collected on the PMM Server.

What resolution is used for metrics?

MySQL metrics are collected with different resolutions (5 seconds, 10 seconds, and 60 seconds by default). Linux and MongoDB metrics are collected with 1 second resolution.

In case of bad network connectivity between PMM Server and PMM Client or between PMM Client and the database server it is monitoring, scraping every second may not be possible when latency is higher than 1 second.

You can change the minimum resolution for metrics by the following way:

  1. Select the PMM Settings dashboard in the main menu.

    _images/pmm-add-instance.png

    Choosing the PMM Settings menu entry

  2. In the Settings section, choose proper metrics resolution with the slider. The tooltip of the slider will show you actual resolution values.

    _images/pmm.settings_settings.png

    Choosing metrics resolution on the Settings dashboard

  3. Click the Apply changes button.

Note

Consider increasing minimum resolution when PMM Server and PMM Client are on different networks, or when Adding an Amazon RDS MySQL, Aurora MySQL, or Remote Instance.

How to set up Alerting in PMM?

You can make PMM Server trigger alerts when your monitored service reaches some thresholds in two ways:

Both options can be considered advanced features and require knowledge of third-party documentation.

Either with Grafana Alerting or with Alertmanager you need to configure some alerting rule to define conditions under which the alert should be triggered, and the channel used to send the alert (e.g. email).

Grafana Alerts are already integrated into PMM Server and may be simpler to get set up, while Alertmanager allows the creation of more sophisticated alerting rules and can be easier to manage installations with a large number of hosts; this additional flexibility comes at the expense of simplicity and requires advanced knowledge of Alertmanager rules. Currently Percona cannot offer support for creating custom rules so you should already have a working Alertmanager instance prior to using this feature, however we are working hard to bring an integrated Alertmanager solution to make rule generation easy!

How to set up Alerting with Grafana

Alerting in Grafana allows attaching rules to your dashboard panels. Details about Grafana Alerting Engine and Rules can be found in the official documentation. Setting it up and running within PMM Server is covered by the following blog post.

How to integrate Alertmanager with PMM

PMM allows you to integrate Prometheus with an external Alertmanager. Configuration is done on the PMM Settings dashboard. The Alertmanager section in it allows specifying the URL of the Alertmanager to serve your PMM alerts, as well as your alerting rules in the YAML configuration format.

More details on the Alertmanager and its alerting rules can be found in the official Alertmanager documentation, which also provides plain examples of the alerting rules.

How to use a custom Prometheus configuration file inside of a PMM Server?

Normally PMM Server fully manages Prometheus configuration file. Still, some users may want to be able to change generated configuration to add additional scrape jobs, configure remote storage, etc.

Starting from the version 2.4.0, when pmm-managed starts the Prometheus file generation process, it tries to load the /srv/prometheus/prometheus.base.yml file first, to use it as a base for the prometheus.yml if present and can be parsed.

Note

The prometheus.yml file can be regenerated by restarting the PMM Server container, or by the SetSettings API call with an empty body.

You can find more details about using a custom Prometheus configuration file with PMM in a separate blog post.

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