MongoDB allows clients to safely retry writes in the face of certain errors where the client believes the database did not apply a requested change but the database actually applied the requested change. The feature is called Retryable Writes. 

Currently MongoDB does not generate any metrics regarding retried writes. It's not possible to answer the following question:

• How often are writes retried
• What is the duration between the original write and the retried write

The server should provide the relevant metrics to answer the questions above and any other relevant questions regarding the use of retryable writes