Frequent append operations are often essential for tasks such as recording log files, archiving data, and performing backups, which support later analysis and processing. This topic discusses the principles of append-only writes and provides recommendations on how to use them effectively for reliable and efficient data writing.

Working principles

The way FSX implements append-only writes differs depending on the bucket type. Specifically:

When appending data to an object in an FNS bucket, TOS uses the UploadPartCopy API to copy the existing data, and the UploadPart or PutObject API to upload the new appended data. In this scenario, one open operation supports only one flush operation.

When appending data to an object in an HNS bucket, TOS uses the AppendObject API. In this scenario, multiple flush operations are supported on appended objects.

Recommendations

When appending to objects in FNS buckets, first perform an open operation, then a flush operation. Only one flush operation is permitted per open operation. For objects in HNS buckets, there is no need to reopen them after appending. You can perform multiple flush operations after opening them once.

To avoid multiplied requests and performance degradation caused by frequent open and flush calls, we recommend prioritizing the use of HNS buckets in frequent append-only scenarios, since HNS buckets support multiple flushes in append-only mode. For a detailed introduction to HNS buckets, see What is hierarchical namespace.

Last updated: 2025.11.25 14:05:57

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