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Does JuiceFS allow the user to specify the hash of a file when uploaded? And then to read that hash back later?

Otherwise there’s no end-to-end integrity check.

The S3 API allow user to specify the hash of content as HTTP header, it will be verified by the JuiceFS gateway and persisted into JuiceFS as ETag.

With POSIX API or HDFS, there is no such API to do that, unfortunately.

surely you mean that the FS should calculate the hash on file creation/update, not take some random value from the user. but I agree that a FS that maintains file-content hash should allow clients to query it.

No, the FS should verify the hash on creation/update. Otherwise corruption during creation/update would just cause the hash to match the corrupted data.

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