System Metrics (applicable for Linux based systems)

In the event that you would like SQL DM for MySQL to use SSH when communicating with this server, you can configure it from this tab. SQL DM for MySQL disables SSH communications by default. In order to use it, you need to click the Enable System Metrics switch. Doing so provides a series of configuration options needed to enable SSH on the server.

Please refer to System Privileges for further details of privileges needed for this feature.

If SSH tunneling to MySQL is configured successfully for this registration you can use those same details here too, provided that SSH tunnel user has enough privileges.

Using SSH connections

To create a SSH connection you need the following details:

• SSH Host: Host of the machine on which SSH server is running.
• SSH Port: Port on which SSH server is listening. By default, it is 22.
• SSH Username: Username to access the SSH server (Note: not the MySQL server).
• Authentication type: Specify the type of authentication to use. This can be either key based or password based.
• If you have specified Authentication type as Password – Provide the password.
• If you have specified, Authentication type as Key – You should note that SQL DM for MySQL only supports ”OpenSSH standard key format” for key based authentication in SSH connections.
  • Private Key: Paste the content of your private key file. Again, do not specify the path to your private key file.
  • Passphrase: Enter the passphrase for your private key file (if any). This can be left blank, if no passphrase was given for the private key.

Define the collection interval for every server as you want

You can also define the time interval between two successive retrievals of data. For production systems a setting between 2 and 10 minutes is a good place to start.

Data retention time frame

SQL DM for MySQL is designed for storing large amounts of data for long periods of time. Data collected before the specified time frame is purged automatically. Time frame may be specified in seconds, minutes, hours and days for a particular server.

Base time

For calculation of uptime-based counters the current value of each status variable is compared with either of those,

• server status variable ‘uptime’
• server status variable ‘uptime_since_flush_status’
• SQL DM for MySQL ‘base time’ setting

If SQL DM for MySQL ‘base time’ setting is defined and server status variable uptime_since_flush_status is available then, uptime_since_flush_status is used, if it is not available then base time is used.

The reason for this implementation is that if FLUSH STATUS is executed with a MySQL server, the server status variables are reset to the same value as after a server restart. There is one important exception however and that is the ‘uptime’ status variable itself. This single status variable is not affected by FLUSH STATUS.

So, to get true uptime-based counters in SQL DM for MySQL with servers that do not support the uptime_since_flush_status variable you need to define a ‘base time’ in SQL DM for MySQL greater than or equal to the time where FLUSH STATUS was executed last time.

But also if uptime and/or uptime_since_flush_status is large (‘old’) you may use ‘base time’ setting to analyze uptime-based counters on an interval defined by you. For instance, if the server has been running for months you may choose to analyze uptime-base counters based on data collected from a specific time only as you have defined it.

Also, note that if the ‘base time’ is smaller than uptime (or uptime_since_flush_status if available), then ‘base time’ setting is ignored. Using a ‘base time’ larger than ‘uptime’ and/or uptime_since_flush_status, then base time is considered. If a base time is in future, then most recent collection time is considered (similar to Delta).