On-Premises to S3 DataSync task sometimes fails with "Deferred error: pwrite ... Input/output error"

Question

We run a daily on-premises data upload to s3 over a DirectConnect network. While the daily task has been running for several months now, in the last week we have seen the daily upload task fail twice with the following Execution Status:

```
Transfer and verification completed. Selected files transferred except for files skipped due to errors. If no skipped files are listed in Cloud Watch Logs, please contact AWS Support for further assistance
```

The cloudwatch log had the following error:
```
[ERROR] Deferred error: pwrite(name="", size=262144, offset=60030976): Input/output error
```

I can't find any mention of this error (and how to fix it) in the documentation, aws re:post OR in a web search. How can I debug the underlying issue?

Answer

This error can occur if there was a file that was not able to be written to the destination on the first attempt. This can occur if there is a network disconnect or disruption during the transfer or the destination is overloaded. If these errors continue, you can start by inspecting your network at the time the ```Input/output error``` occurred.

On-Premises to S3 DataSync task sometimes fails with "Deferred error: pwrite ... Input/output error"

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