A backup application is performing a multipart upload of a large database dump to S3. All parts are 5 MiB except the very last part, which is smaller. Is this multipart upload valid?
- No, because every part including the last must be at least 5 MiB
- Yes, because there is no minimum size limit on the last part of a multipart upload
- No, because all parts must be exactly the same size
- Yes, but only if the smaller last part is uploaded first
Correct answer: B. Yes, because there is no minimum size limit on the last part of a multipart upload
AWS's published multipart upload specifications state that part size must be between 5 MiB and 5 GiB, but explicitly add that there is no minimum size limit on the last part of a multipart upload. Since every part in this scenario is 5 MiB except the final, smaller part, the upload conforms exactly to this rule, making the second option correct. The first option is wrong because it misapplies the 5 MiB minimum to the last part, when AWS explicitly exempts it. The third option is wrong because multipart upload never requires uniform part sizes; parts can vary in size as long as each (other than the last) meets the 5 MiB to 5 GiB range, and parts can even be uploaded in any order or in parallel. The fourth option invents an ordering requirement that does not exist: part numbers determine the final assembled sequence of the object, not the order in which they are physically uploaded, and the smaller final part does not need to be uploaded first or last relative to the others.
Source: AWS S3 documentation: Amazon S3 multipart upload limits — part size 5 MiB to 5 GiB, no minimum on the last part