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We had an issue, where one of our kubernetes service not able to read the certificates stored in NFS volume. I could see from NFS stats there were retrans happended ( 33 times ) from the status on that particular time. Does the retrans cause any issue with the application service ?

Also, we had issue for a service only in one vm, other services running on different vm but uses the same NFS dont have any isssues.

Here in the above scenerio, we were able to fix the issue - by restarting the service.

Jax
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1 Answers1

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Yes, NFS retrans can affect an application's service. The configured duration of nfs retrans varies. If there are several timeouts beyond what an application can endure gracefully, then yes this could be a problem. NFS performance can be dependent on the network (e.g., the proximity of one server to another, and congestion between the two servers).

NFS may facilitate synchronous communication; NFS relies on network connectivity, and its performance varies. Applications that rely on NFS may have minimum performance levels that NFS cannot meet due to delays or performance issues.

Oracle says "one of the major factors affecting NFS performance is the retransmission rate."

RedHat in their man page for NFS says that file operations can be aborted or will involve a "server not responding" message if enough retransmissions happen.

Modern messaging systems facilitate asynchronous communication. There has been a recent widespread adoption of messaging tools in the industry. Some companies re-architect back-end systems to leverage messaging systems. However NFS can still be useful to support application services and possibly the data requirements.

This 20 year old book may be helpful: Managing NFS and NIS: Help for Unix System Administrators Second Edition by Mike Eisler, Ricardo Labiaga, and Hal Stern. Please refer doc1 and doc2.

Abhijith Chitrapu
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