Mongo Transactions Test

Rollbacks are expensive operations and will have to be avoided at all costs. Using the Mongo Transactions test, administrators can be instantly alerted if more than a permissible number of rollbacks are happening on a target MongoDB server. In addition, the test monitors transaction checkpoints. A checkpoint acts as a recovery point for an operation. When a transaction attempts to modify the data in a data file, MongoDB presents an in-memory snapshot/copy of that data and allows changes to be made to that data. While writing the data in the snapshots to the disk, MongoDB creates restoration points between the snapshots, called checkpoints. If these checkpoints are not created frequently, it only means that data is not written to the disk regularly; this increases the risk of data loss during recovery. To avoid this, administrators can use the Mongo Transactions test to monitor the time taken for creating the most recent checkpoint and thus, quickly detect delays in check point creation or writing to disk.

Target of the test : A MongoDB server

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for the Mongo database server being monitored.

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed.

Host

The host for which the test is to be configured.

Port

The port number at which the specified host listens.

Database Name

The test connects to a specific Mongo database to run API commands and pull metrics of interest. Specify the name of this database here. The default value of this parameter is admin.

Username and Password

The eG agent has to be configured with the credentials of a user who has the required privileges to monitor the target MongoDB instance, if the MongoDB instance is access control enabled. To know how to create such a user, refer to How to monitor access control enabled MongoDB database?. If the target MongoDB instance is not access control enabled, then, specify none against the Username and Password parameters.

Confirm Password

Confirm the password by retyping it here.

Authentication Mechanism

Typically, the MongoDB supports multiple authentication mechanisms that users can use to verify their identity. In environments where multiple authentication mechanisms are used, this test enables the users to select the authentication mechanism of their interest using this list box. By default, this is set to None. However, you can modify this settings as per the requirement.

SSL

By default, the SSL flag is set to No, indicating that the target MongoDB server is not SSL-enabled by default. To enable the test to connect to an SSL-enabled MongoDB server, set the SSL flag to Yes.

CA File

A certificate authority (CA) file contains root and intermediate certificates that are electronically signed to affirm that a public key belongs to the owner named in the certificate. If you are looking to monitor the certificates contained within a CA file, then provide the full path to this file in the CA File text box. For example, the location of this file may be: C:\cert\rootCA.pem. If you do not want to monitor the certificates in a CA file, set this parameter to none.

Certificate Key File

A Certificate Key File specifies the path on the server where your private key is stored. If you are looking to monitor the Certificate Key File, then provide the full path to this file in the Certificate Key File text box. For example, the location of this file may be: C:\cert\mongodb.pem. If you do not want to monitor the certificates in a CA file, set this parameter to none.

Measurements made by the test
Measurement Description Measurement Unit Interpretation

Initiated

Indicates the rate at which transactions are initiated.

Transactions/Sec

 

Committed

Indicates the rate at which transactions are committed.

Transactions/Sec

 

Rolledback

Indicates the rate at which transactions are rolledback.

Transactions/Sec

Ideally, the value of this measure should be very low.

Rollback rate

Indicates the percentage of initiated transactions that are rolled back.

Percent

A value close to 100% is a serious cause for concern, as it implies that almost all transactions have been rolledback. Rollbacks consume processing overheads excessively and reduce database performance.

Recent checkpoint duration

Indicates the amount of time taken to create the most recent checkpoint.

Seconds

An increase in this value under steady write load may indicate saturation on the I/O subsystem.